MF with interchangeable lenses isn't going to be cheap.

Inexpensive, Affordable, Light is going to be TLR territory; a Yashica-Mat with a 4 element lens is going to be budget and high quality. Rolleiflex Automats are also excellent quality but sometimes more expensive and somewhat collectible. I really don't consider the lack of interchangeable lenses for most TLRs a problem. It keeps them light and purposeful. Image quality vastly exceeds 35mm film because of the larger negative.

Up the scale the interchangeable lenses, the cameras get heavy and big and more expensive. You're looking at systems things like Pentax 67, Bronica, Hassleblad, Contax 645, Mamiya, Rollei sl66, and so on. I've got a pentax 67 and a couple lenses but it doesn't get used as much as the TLR.