95 Integra GSR; 160k miles

This past Friday on the way to work the car stalled and wouldn't
re-start. SInce it was rainy and I had a wet-weather start problem some
years ago I thought it might have been the distributor cap, so I
replaced that; when the car still wouldn't start I had it towed to a
nearby fixit place.

Their diagnosis was: the distributor had failed. They estimated $500
for a new distributor, and I choked and agreed to it.

Then I looked up distributor replacements for this car on the web and
saw them ranging from $180 to $320. I called the fixit place back and
challenged them on it; the desk guy couldn't explain the price
difference. We agreed to wave off until he could call an Acura place
for a parts quote, thinking it would be different than their
after-market supplier's price.

My question: is the distributor a modular part that bolts into place,
or is there more to it than this? If it's a fairly simple operation I'm
tempted to tell these guys to go soak their heads and replace it
myself.

I'd appreciate feedback. Thanks!