Josh, the best way to do it would be to make a list of the sizes your car takes then buy sleeves of 10 packs of each size bearing. You get them for about $1 per bearing and you will have extra bearings in your box for when you need them. The last thing you want is to buy 1 bearing kit, and then have a bearing failure at the track and you have to go home because you dont have any spares. I can help if you want, send me PM. Answer-RC, Avid, and Ready Rollers all make some great bearings that are cheep and last awhile if cared for properly.