I just got a couple of good pieces off of ebay. You have to be real patient, but you can get some good deals. I got two nice pieces for just over $45.00 delivered.
I got all the wood from my 150G from www.aquariumdriftwood.com They have some great show tank style pieces, granted IMO they overstate the size of their wood(lol)....I have 2*super pieces, 3*large pieces and 2 of the large size assorted packages in my 150 And to me....it could probably stand a little more, granted in the last year or two my pleco has really done alot of mowing down on the wood...after Xmas its getting overhauled with more wood and less plants for sure.