Car: '95 Camry, Inline 4, manual

A little while ago I had an on/off problem with putting the car in gear. I would push the clutch in, but the tranny would make a horrible grinding noise when you tried to put it into 1st gear from a start, and would occasionally also not go into 2nd. I noticed that if I pumped the clutch fast and repeatedly, it seemed to fix the problem (at least some of the time). Anyway, this would only happen very rarely, maybe once every couple of months, and once I managed to get it to go into gear, it would be fine after that.

Anyway, yesterday morning I go to start my car and it won't go in gear again.. I pump it a bunch and nothing happens. I tried for quite a while doing anything I could, and it just wouldn't go into gear this time. Oddly, it will go into 1st gear when the car is off--I'll put it there with the clutch in, and start the car, and then let it out and can drive away, but it won't go back into 1st when i let it out.

Another problem that's been constant and on going for many months is the engine and/or transmission shudders excessively when letting the clutch out into 1st gear. Not sure if this is related--I don't know much about manual transmissions or camry's in general.

We take it to a mechanic who basically said they need to replace the entire gear box. didn't really explain further. another guy said it sounded like a clutch problem and not a gear problem. Any thoughts? anyway, quotes ran between $700 and $1400 to fix the problem, so I'm hoping if i do spend that kind of loot that it will definitely fix the problem. Anyone have any suggestions or advice?