I'm in the same position as awarnes. We don't travel far and stay within a few hours drive.
Anyway, I bought 6 of that size last year for $125 each. They are some no name brand but load range E.
I would say you should be able to get a decent tire for under $200 a piece, but that's a guess.
I can't stress enough, don't run those tires, even if they are only just a little bit cracked.
That's how mine where when I decided I wasn't going far, and I only run about 60 mph, and the weather wasn't extremely hot.
Long story short, within 10 miles of the house, the tread came off one of the inside duals. Had it been on the other side, it would have wiped out the gray, and possibly the black water tanks. Fortunately, there was little damage to the underside of the coach.
On a side note, the tires where all properly inflated, I ALWAYS check the tires before we go on a trip. As a matter of fact, that tire (what was left of it) held air for a few weeks after that!