IDK know if they are that much - pretty sure my roots disty priced me out at $2800ish for a 59 - i'd have to guess a 45 would be less.
They completely rebuilt my 59 3 weeks ago for $1700, and that included time to remove it from the machine, put it back in, and then laser align the blower to the direct drive coupler. I'm thinking the actual parts and labor just for the rebuild was $1400
You might find your local roots distributor and give them a call - you might be surprised how cheap it is to go that way if you can get it out and back in.
You may even want to call around to several roots disty's to see if they have a rebuilt one stocked. They may even give you some $$ for your core.
Good luck!