1) Building a robot yourself is the best experience.²
2) Buying a decent feather isn't cheap.³

² but with help from experienced roboteers you can avoid a lot of pitfalls and moneysinks.(and having the basic tools available helps too)
³ even the cheapest featherweight ready to run will cost you £200, and then you have a wooden or cutting board armored box. A full balls out weapons blazing titanium monster can easely go £2000+