clutch

i have a bagged 93 isuzu pickup... it been driven for a while by my friend for a while now and i just drove it today... the clutch is REALLY spongy... it takes a LOT of effort to push in and doenst comes back really slowly... i stopped at a car place and they said it would be $400 - $500 parts and labor... is that reasonable and is it something that i could do on my own? i have tools but dont have what is required to drop the transmssion.... any help would be really helpful thx