House rentals on the cost of Italy

I don’t think you’ll find that here, as this Forum is about non travel agents, just regular people, sharing travel tips and asking questions.

you probably know about Schengen 90/180 limits and the restrictions on long term leases, but perhaps you are doing that in conjunction with a Residence permit or visa, so forget this. But if not, and you don't, best be aware

I expect that the cost will be directly related to location and size...

Gastal, where in Italy do you intend to rent? If Umbria, maybe check out real estate agent (not travel agent) Luana Zingarelli. We once used her service for an apartment overlooking the main square in the town of Bevagna - that apartment was excellent.
Otherwise perhaps check out VRBO, booking.com, Sawdays and the other usual suspects.
Sometimes, an email to the Tourism office at your destination can result in them providing listings.
Good luck.

I am done. the end

correction:
Luana Zangarelli (not Zingarelli)
Her 'Italy to Rent' company is based in Spoleto.
I am done. the speling