A Sinar F2 with lens for $750.00 could be a good deal depending on what lens comes with it, condition of everything and what extras if any come with it. I have seen real nice ones sell for around that without a lens on Ebay. Of course it has to be the F2 which is the last F series that was made.
You can buy a nice Cambo/Calumet for $200.00 and less. I have seen them go for $150.00 and even below $100.00 if you don't care about age or cosmetics.
You can buy a nice Sinar F for $300.00 if you are patient. Later F models, the P series and earlier Norma's are more money.
If you want something cheap then Cambo/Calumet can be a great way to go. Toyo's are said to be nice but I have no experience with them. If you can afford Sinar and want a monorail, I would go with that. Sinar is a great system camera.
The best advice I can give you is not to get in a hurry and do some research before you buy anything.