When I bought my kayak from West Marine, BOTH double and single decks were included into the package as well as two seats, inflatable foot brace, foot pump, and the carrying bag. Note that nowadays many stores show the “low” price (usually still higher than WM) and then you discover, that for EVERYTHING into the package you have to pay EXTRA!
One has to check carefully what is included into base package/price and what is optional and will be cost EXTRA. Important is to compare the costs of the parts and find the cheapest combination of basic and optional.
Pumps
Bellows Foot Pump from Advanced Elements- #AE2001, Price: $19.99 , which usually is included into the package (make sure that it is in your package) is generally enough to inflate your kayak in 8 minutes.
5000cc air displacement with each stroke
Compact size
Inflate and deflate modes
Extra long air hose
Full kayak inflation in less than 8 minutes
Double action hand pump delivers air on up and down strokes.
Deflate mode
5-ft accordion-style hose interlocks to the pump, so that it doesn't fall off while you're pumping.
High pressure, up to 14.7psi
18 inches tall.
Ergonomically designed handle and foot plate.
Seats. Two Regular AE seats are included into the AE basic package and provide satisfactory comfort even on the long trip. They looks almost like Lumbar Seat shown below, but had no inflatable part.
Price: $39.99 Adjustable lumbar cushion!
On the AE forum some people were complaining on two points: back support and wet bottom.
One can easily provide better back support buying special high back kayak seats from various sellers (see below one of the choices).
Of course it’s extra money: from $40 to $109 US and more.
or
As to the wet bottom the simplest decision is to put small inflatable cushion ($5 US) under the seat. I often use the foldable touring seat ($10 CND) instead of this cushion (put it folded under my kayak seat, then using it at the campsite on direct purpose).
Canadian Tire Escort Stadium Seat Pad, PRODUCT #76-1599-0, REG $16.99 CND, often on sale for $9.99 CND
Foot Brace
Some people feel needs in additional foot brace when paddling. They can buy inflatable foot brace from Advanced Elements - #AE2012 for $29.99 US. It is for the front person, the rear person has inflatable foot brace supplied with the kayak and sitting at the back of a front person.
Convertible Decks from Advanced Elements - #AE2021/AE2022 Price: $49 -$69 US - expand the versatility of the AdvancedFrame2 Convertible Kayak allowing you to create a closed deck kayak that is easily paddled by one or two persons. Durable, zippers into place, and will accept an optional spray skirt!
One of them can be included into basic package (usually double one), another one being optional. When I bought from West Marine BOTH decks were included at the basic price!
Spray Skirts. Not everyone paddling on AF Convertible needs and uses spray skirt. I myself bought one, but had no experience in using it yet.
There are two slightly different skirts sold for AF kayaks: Touring spray skirt AE2007 ($64-68 US) and Packlite spray skirt AE2026 ($39.99US). I have Touring one and think the adjustable suspender straps are very helpful.
Touring spray skirt AE2007 ($64-68 US)
Touring spray skirt AE2007 ($64-68 US)
Packlite spray skirt AE2026 ($39.99US)
Backbone
Is a great invention and improvement AE did for their inflatable AF kayaks. It’s like a spinal column imparting additional rigidity and higher tracking ability to the kayak. Almost everybody who used it with the AF kayaks agreed that it’s worth to buy and install, especially when you are going to paddle on the flat water like Canadian Lakes .
The Backbone is inserted under your floor cushion while your kayak is deflated. Once the kayak is pumped up, the backbone creates a bow-to-stern frame which enhances performance and rigidity; while the bow-to-stern beam is straight, the side-to-side silhouette has a slight v-bottom. The backbones for different kayaks are of different length, the longest being for AF Convertible - AE2023-AFC - 126.5 inches long; it consists from 3 shafts, the longest one length is 35" ($99 US).
Paddles
I did not recommend to buy paddles at WM. I bought their Composite Fiber Pro 340 and one of them was broken on a flat water with no special efforts from my part. WM refund it with no words and I bought Carlisle fiberglass paddles Magic and Magic Plus 230 cm at Pro Bass Outfitters. They were on sale and cost me $89.99 and $109.99 CND. I used them actively the whole summer 2009 and hope to do so in 2010 – they are still in excellent conditions.
Many experienced paddlers advise to have a spare paddles on board and usually recommend cheap four piece aluminum paddles for this purpose (for example this Cascade from Airkayaks.com http://www.airkayaks.com/cascade.html).
Some useful bookmarks about Advanced Frame Convertible kayaks.
Advanced Elements
very nice and detailed description of AF Single and Convertible by an experienced sea-kayaker.
http://www.airkayaks.com/ae1007-07.html - detailed description of various packages with the prices from one of the best (not the cheapest) suppliers (see picture below).
http://kayakyak.blogspot.com/2006/03/inflatable-kayaks.html - some good words about Advanced Frame from B.C. in 2006,. Especially in Paula’s comment
Backbone “poem” - http://kayakyak.blogspot.com/2009/10/backbone.html
Fishing devices in the AF kayaks:
This one was done for the Convertible! - http://suntan-suntan.blogspot.com/2009/07/bulding-rod-holders-for-advanced.html
How to paddle? - http://www.youtube.com/watch?v=zNHdmLZmZg0