about how much do you think getting an alto saxophone completely repaired

It all depends on what you mean by 'completely repaired'. Check over & adjust? Overhaul - good clean, new pads & key corks, & regulate? Is there any dent work soldering or other mechanical work to do?.
Then every technician has their own pricing structure - what one might charge $200 for another will be $400. Also when comparing prices you must ask for full details of what is included - are parts extra or part of the price. One tech's 'service' might not be the same as another's.