RC tanks is a fun hobby and as been mentioned, plenty to do with upgrades and parts availability. If you are into modelling, there are many conversions that allow you to buy several of one tank and convert them into other variations. The little Pz III is an excellent tank both for reliability as well as conversion kits. The New KV I and Sherman will also allow plenty of work in this area. Any questions you have about RC tanks will generally be addressed by several members. Have fun.