Personally, I’d get all I could. I’m using 2 starter kits, 2 hardware kits, extra metal from vexlabs, about 14 motors and 12 servos, 2 wheel kits, 1 encoder kit, 1 ultrasound kit (wish I had a few more) and several sprocket and gear sets. I have one bot that stays in working order, and use the rest of the parts to prototype other bots. I typically have 2-3 bots on the workbench at any given time, and the extra parts/motors make it easy to do so.
Of course, if your only looking for 1 good bot, then I’d say at least 6 motors on hand and 4 servos. You can build most any armature with a combination of those, and have spares just in case (I’ve toasted a servo already). I’d also get a few ultrasounds if you can find them, but the encoders are kinda useless because they don’t record direction and they are bulky. You can code around the direction issue somewhat, but it still isn’t optimal. The extra hardware and wheels are pretty handy too.
I too have thought that “just buy it all” was the solution but I am trying to stay within reasonable quantities even with the favorable Radio Shack pricing. Considering that the supplies are shrinking quickly, it would seem to about time to finish buying extras and so I am asking what is reasonable to keep on hand.
As far as motors and servos I’d go for eight motors and at least a couple of servos. Most robots I’ve built so far don’t have much call for servos, but almost all of the bots have used at least 6, 7, or 8 motors. 2 or 4 motors for drive train, 1 motor for each axis of movement on any arm built, 1 or 2 motors for elevator/lifting mechanisms. The servos that have been used were usually for pan and tilt mechanism for sensors like the ultrasonics.
As far as hardware… 1 or 2 gear kits 1 to 4 chain and sprocket kits (and more chain from vexlabs ala carte!) at least 2 extra hardware kits (or a lot of ala carte metal from vexlabs!) 2 omni wheel kits and 1 to 2 tank tread kits (they make awesome ball harvesting conveyors just check out any pictures of 2005/2006 Half Pipe Hustle bots!)
I created a spreadsheet that lists all the parts available at the time I made the spreadsheet, and that used some seat of the pants fomulae to compute what to buy to in order to create a user-defined number of “complete” Vex robotics set-ups.
If I get a chance to review and tweak the spreadsheet soon (to insert changes due to lessons I have learned), I’ll then figure out how to post it somewhere that folks can read or copy it for their own use.
Bottom line - No answer for you tonight; but a pretty good one soon.
Can you wait a few days? If not, send me a private message or an email.