Belt: $30
Tensioner: $50
Upper Idler Pulley: $20
Lower Idler Pulley: $30
30" Breaker Bar: $20

You can lube the pulleys to quiet them down for awhile, not a lot of water gets in there to wash it out. I've got a small tip bottle of drilling fluid that I've used in the past to shut up pulleys until I have time to replace them. Spray lubricants work as well, just need to use something that can handle 300ºF.

If the seal is not blown out, you can pull it, spray some PB blaster and let it soak, clean out with brake cleaner, then repack with hi-temp grease and replace the seal. I've had bearings go a few years after doing this before squeaks returned. I started using this method when sealed bearings became the craze in the road and mountain bike industry and were expensive as hell (90's). I have bearings from that decade that are still in use.

If you can spec the bearings or get mfg part numbers off them, find them, and have access to a press, tensioners and pulleys are more like $10 each.