New 8 speed cranksets will be pretty much low end (as you've found). If you want a higher end 8 speed crankset you'll have to look used or NOS.
If a 9 speed crankset will work (I don't know, maybe someone can comment), that will be easier to find than an 8 speed crankset. Something like a Shimano Deore M590 crank is very solid, reasonably priced, and not too hard to find.