Phone some local dealers to see if they recommend anyone. Not sure what you consider "an arm and a leg" but $500 - $1000 isn't uncommon for an electrician.
If you are concerned on the total cost, go buy the 50 or 60 amp breaker, the #6 wire, dig any required trench, feed the wire from breaker to tub and just hire an electrician to physically hook it up.
Steve