John, what are you building? Which rudder to recommend totally depends the intended use of kayak.

Over the past few years I've installed a few different rudders so here's some thoughts on each. Prices are retail for the rudder only and for comparison only. Foot brace system is extra.

Composite Engineering Mohican Kick-Up Rudder ($250 direct through Composite Engineering)
If you're building a dedicated race boat, consider installing Ted Van Dusen's system. It does kick up but does not fully leave the water. On Wil's Wahoo we added an up haul to it. The blade extends straight backward when tensioned. For a race rudder it's a quality bit of kit with the bracket and gudgeon made entirely out of carbon fiber. The blade is anodized aluminum and spring loaded. It's also dead flat with no shape to it, just beveling on the leading and trailing edges. Some people have made custom carbon blades that are shaped. The entire system is designed to be light so the parts are pretty thin in cross-section. The pintle is only 1/8" in diameter for example. I wouldn't use it for hard touring. If you do decide on installing one, order it now. You might have it by the fall. Seriously. Ted is super busy, especially during the race season.
http://comp.mybigcommerce.com/rudder-mohican-kick-up-blade-sizes-1-2-3/

SmartTrack ($130 through Stellar Kayaks)
For hard touring I'd use a SmartTrack rudder system. The parts are beautifully machined aluminum, stainless steel with a fiber reinforced resin blade that has a hydrofoil cross-section. The blade retracts straight up. The cables are very easy to adjust with the wedgies. Spare parts are fairly easy to come by. Below is their "Race" version. It's a bit more compact and lighter than the standard Compact hub but uses the same blades. I bought the one below through Stellar Kayaks.
http://stellarkayaks02.businesscatalyst.com/catalog-1/Parts/Steering/race-rudder-with-boyonett-pin

KayakSport (€100.00, about $135 through Nelo)
The KayakSport system (an older one sourced from a Nelo for this install) is a robust system. It's very simple with few parts to wear. Everything is fiber-reinforced plastic. Like the SmartTrack, on this one the blade retracted straight up.
http://www.nelo.eu/shop/en/touring/rudders/rudder-kajaksport.html

Sea-Lect Designs TruCourse ($110 through Duckworks)
The rudder is an interesting system. It doesn't work like any of the other kick-up rudders. The entire blade is free floating on glides so that it slides up and forward over the deck during retract. Personally it's a bit overly complex with a lot of parts that could wear. I'm installing two this summer because the price is right. It's definitely the least expensive option. No pictures yet. Found this one online showing it retracted and in use.).
http://www.duckworksbbs.com/hardware/canoe-kayak/sd748300/index.htm

For foot braces I would definitely install a surf ski style foot board with peddles. It's so much more comfortable and than plastic foot braces on rails. I don't like tiller systems. I don't like having the tiller between my toes. The peddles also seem more intuitive. The foot boards are pretty simple and can also be made to be very light and strong.

While we're on the subject, for steering lines I now mostly use Dyneema cord in lieu of 1x19 stainless wire rope. It's strong, doesn't stretch, and is lighter and much easier to work with.

Any questions shoot me a message.