Clutch Help!

[GWAPITO69]

i was driving my car to work and everything went good except for that brake but after work i started my car and when i press on the clutch the pedal and that darn thang went all the way to the floor. i checked underneath the car and the fluid on my master cylinder went less than the minimum level so i'm guessing that i have to change the clutch slave cylinder. and the master cylinder i just replaced it last year... is that the only thang i need to replace.. the folks down here wants to charge me $350.00 for the repair... what do you guy's think? do i have to replace the clutch disc and pressure plate too? need info so that i can buy what i need to buy