We made our own backdrop out of gatorboard and trade show material and stuck our own stuff on it. We had an interlocking set up and the whole thing folded down from an 8' x 12' to a 4' x 8' and was so lightweight it wasn't funny. We also had a 1/2 height one for smaller shows.... 4' x 12'
If you're worrying about spending $300 or $500 dollars on this or that..... you probably shouldn't be doing it, yet.
The booth costs a few thousand and your props another $2,000 or $3,000. We usually gave away a nice sized television and all the runners up were entitled to a 15% discount if used within like 90 days. You're trying to attract large clients and show off your capabilities and wares. If you go in looking cheap, you're only gonna attract cheap............. customers.