I guess you just get better deals than I do, since you're obviously soooooo... much smarter than I am. I looked back at the invoice just to see what I was charged. The two main tubes were $95 each and the front with a curved valve stem was $120, so with Tax the parts were ~$350 (I checked the prices on Aircraft Spruce and I was charged a little more, but not a lot). I have wheel pants and since we were there we packed the wheel bearings so they wouldn't have to be done at annual. My memory was a little off, the total for that work out the door was $607. I am in a community hangar so no working there. Texas is about 110 degrees on the ramp in summer, so I'm not sure I'd want to spend a day working on it to save $257 either.
As to the original repair: I guess when you call an A&P you've never meet on a Sunday and ask them to stop what they're doing, load all their tools and a compressor up, drive over an hour each way, supply a tube, and work out in the heat for a couple of hours. They just say, Oh for you 93K, no problemo, $50. Now, if it was one of those other dumbass rich pilots it would be $300.