>>They said that the front transmission/gearbox is shot and needs replaced and they expect it to cost around $250.
Ariens does not source the old main parts of worm, shaft or gear for that gearbox anymore. They only offer a replacement gearbox assembly which includes the drive shaft with worm, gearbox and rake arms as an assembly. It’s $179 online. There’s a thread on it with pictures here :
http://www.abbysguide.com/ope/discussions/52242-0-1.html
Possibly they may have new parts from old stock or quoting with used parts for the repair like have a complete assembly out of a similar bucket.
>>If I had the time I would try it myself but I'm not sure how available the parts are.
The repair is not so difficult technically but rust makes it a bear. The pulley, auger support bearing, pulley flange and impeller will probably be rust frozen and difficult to deal with. You might have to bring the impeller to a shop to have it heated and put in a press to get off - $50-$75.
>>Are the replacement parts going to be of the same quality as the 1995 vintage parts or did Ariens upgrade the gearbox parts in the newer machines?
The original aluminum was a pretty good gearbox. The upgrade replacement assembly mentioned in the thread above is cast iron and seems very….very robust.
Craigslist is a good source for a bucket. They come up all the time but not on demand so you’d have to wait until one came up. It would be cheap and easy to swap out but hit and miss on availability.
On the estimate. If $250 is with the Ariens replacement cast gearbox then that seems like a very good price. But it does not leave much for labor so may not be for the Ariens replacement cast box assembly. If not then I’d ask what parts they are going to use. The replacement could be more if they run into rust trouble which is very likely. Some shops are geared up for that and some are not.
It would be a nice summer project but you are probably pressed for winter.