Speed Triple 2005-2007 are all the same, order parts for 2007. I've ordered from them in the past and you'll get it in about 6-10 days (the longest wait is for them to get it from Triumph). You should be able to get air filter from them. We get 10% discount from bikebandit.
Spark plugs - use the opportunity to change to iridium plugs (CR9EIX) - better, more consistent spark especially in cold, last longer too. The best price I found is eBay store DaveKnowsDeals, where you can easily buy 3 of them, instead of full box of 4.
Oil filter -best source is Amazon, you can buy 2-pack for $9.48 now. Excellent filter, do not get discouraged with mustard colour -you don't see it, and it get covered with road crap almost immediately. Do not waste money on K&N, this is basically HiFlo filter with crappy stamped nut welded on top for additional few bucks. You use it once during filter removal - buy filter wrench/pliers.
Antifreeze and fluids - change to EngineIce, but flush several times with distilled water before final fill. Buy in local Cycle Gear store or online.
About dealer offering once-over for $400 - if he has good reputation and offers to not only look at it but also fix problems in this price - you may consider it. Depends how comfortable you feel doing it yourself, tools, garage space, maybe experienced friend to help. You should check bearings (headstock, wheels, rear hub), brakes, valve clearance, throttle body balance etc. All this you can do yourself if you feel up to it.
You can find more information here or at thespeedtriple.com - use the search function.