I am also 13 and am into building building robots. about two years ago I set out to do the same thing. I have two servo motors controlled by an oopic microcontroller now and the bumpers work although they are broken at the moment. I made many mistakes along the way and it eventually ended up costing me about four hundred dollars I recomend that you read Gordon McComb's robot builder's bonanza. It helped a ton. ask for money for christmas since its comming up and you sound like you need it you may be enticed to use wire wrapping becasue it is cheaper and easier than soddering, but the high gauge of the wire is not heavy enough to carry the voltage to the wires. I suggest that you start your prodject woth two servos on a square wooden board with foam or plastic rc car or airplane wheels. for a prosesser i wish that I had used the brainstem becasue it has more interface examples, is more powerfull, and you can just plug the servos in without having an external power source. It is more expensive than the oopic and the basic stamp, but it is worth it. When you get to the poing where you want to start useing vision, the brain stem is the way to go
formatting link
-- brainstem and excellent parts vendor
formatting link
robot builder's bonanza
your parts list should look something like this
1 soddering iron
2 sodder
3 two modified continuous rotational servos (buy these premodified it is a pain other wise)
4 a brainstem/oopic/basic stamp
5 a few battery packs
6 a one square foot board anywhere around half an inch thick (go to the local home depot they have this stuff as scrap)
7a great deal of patientness