I think we need to know a bit more about what you are going to do with it to narrow down what kind of fixed blade you are after.
Do you want something like a 9in+ chopper or a 4 inch edc knife? Then there is neck knives and knives that bridge the chopper/edc gap.
In general, smaller knives will cost less, so if it is just for collecting you can get a real nice 3.5in or below knife. Possibly a custom depending on what you get and where you get it
Swamprat, scrapyard and bark River knife and tool will probably be your best bets. Beckers would be a solid choice as well.
Hope that helps