What are you keeping them with? If africans, I would not risk some of the more expensive (even low end) ones as they may get eyes bitten, etc. Bristlenose and commons and leopard sailfin and the larger ones are usually fine...and clowns, since they hide all the time.

If youw ant to see your clown more, put some driftwood toward the front of the tank (and only there) - he'll be out on it as they love (and need) driftwood.
Others that aren't too expensive:
Butterfly pleco (L052) - I've seen these for around $15 each (but not always available)
Inspector/contradens/snowball - These can go for $10-20 each depending on size - I got a pair for $30 at a recent auction.
L270, L333, etc - some of these interestingly squiggle-patterned plecos can be found for relatively cheap ($10-30 each depending on size and where you get them)
I'm sure there's others but those are some I'm familiar with.
Oh, and Pet Supplies Plus often has cheap plecos mixed in...usually commons/sailfins but the occasional clown and/or ancistrus sp. variant for a few bucks or well under $10.