A good quality 11" converter should run around 200.00. Other than a loosened stock converter, there's really no inexpensive way to build durability into a converter for performance use. Racing converters like I've used in the race car over the years have cost 4-5 times that amount, for something which can hold up to the demands of full time racing.
Summit sells the StreetFighter 10" converter which is currently in the car...I've found it to be a good value and it's provided reliable service. IIRC, it cost 310.00 back in '95.
You might check with a local trans wholesaler...they may have a line on a supplier which sells generic performance converters, which can (I emphasize CAN) have the same durability and performance as the name brands...and save you some bucks..
To me, given the trouble involved with replacing a bad converter, I'd rather spend the money for decent quality stuff...especially if I'm gonna lean on it..