depending on budget/pocket.. and things that you really like and things that you want.... really difficult sometimes.
Don't buy things you already have, which i tend to do so.
I love the varieties - a friend of mine got something parts/kits at really good price $100-$200 but end up paying $100 for domestic shipping, another 30-40 for fee then other issues with shipping as it contains an Engine had to arrange shipping for $400.
so got to be careful what you can bid and the cost that comes with it.
I also learnt the hard way, don't buy little parts like gears for a few dollars end up paying $30-40 for shipping lol! and buyee fee...