About the cheapest swap I can come up with is a low mileage MA5 out of a Colorado or similar, with a 94-99 (I think) Dakota bellhousing.
There is an MA5 local to me for $450 with 60K, and the bell is $50-100. Still have the cost of a clutch, and any other miscellaneous parts if your car isn't already a 4 speed, plus a hydraulic master cylinder conversion of some type, and it is far from a "slap it in" conversion as the floor and crossmember will need as much work as a T56 swap, but I bet is still cheaper in the end than Tjfly4pay's lockup converter.
The MA5 does have a 3.753 first gear, kind of deep, but I think it's workable. They seem to work well in the Solstice with an LS swap. Seems like a really good match to a high rpm motor, to me.
