WTF? 8-) I have a Commbank 'Comm 2000' EFTPOS terminal here which I use for my computer business, and unless those prices you've quoted are for some super-high-tech wireless EFTPOS terminal, they're absurd. Comm Bank charges me A$29.70 per month for the terminal service fee - nowhere near the figures you have quoted. I'd get it cheaper if I'd signed up for a 4-year contract in January this year and accepted a massive fee to cancel the contract or exit when it next expires, but I opted not to do that. 8-)
I would assume the wireless terminals (which I've seen a couple of outlets use at Modelling the Railways of NSW conventions in the past few years) have a higher monthly fee.
As others have said, using a debit card if the traders can accept those. Most EFTPOS terminals accept debit cards and credit cards as if they are one and the same - it's just the way the bank hosting the buyer's account processes the sale that it different.
Regards,
Craig.
PS. I've cross-posted to rec.models.railroad since I'm curious to get some insight on this issue with regard to exhibitions in the USA. I don't know if the banking rules for EFTPOS, etc. are the same or similar to those here in Australia. How do US model railway/railroad suppliers deal with accepting (or not accepting) payments by credit card at exhibitions?