I don't know how you're checking your prices and which Saturday you're staying on. Onsen resorts on Saturdays are generally tough price-wise. Anyways, using Sat 10/18, I've just had a quick look.

I get 77,800y total including two adults, dinner+breakf at Gora Hanaougi.

Some of the other places... I've just had a quick look, so by no means is this a comprehensive list. These are all places with at least decent onsen, and it's priced for 2 adults with dinner+breakf.

Gora:
Gora Kansuirou (40,000y) - old shinise ryokan
Gora Hanougi Souunkan (46,300y) - don't know much about this place, but looks like a place worth looking into

Sengokuhara:
Hotel Green Plaza (40,700y) - dinner here is nothing special (French or kaiseki at their restaurant); room nothing special either but, on a clear day, you have a great view of Mt.Fuji from the outdoor onsen.
Auberge Ren (50,600y) - French-influenced, so no tatami room here or kaiseki dinner.

Yumoto:
Hotel Okuyumoto (43500y) - very nice onsen area, room okay but a bit dated; you should consider this place.
Tenseien (33600y) - large hotel with regular western-style room/beds, but nice onsens; both dinner & breakf are buffet-style which may work to your favour

I should mention that I've actually stayed at only some of the places above, although they've all been on my list (except Hanaougi Souunkan, which I don't know much about... I just put that on there due to good reviews and good onsen profile)