I was looking at various battery pack welders for making my own MadMaxaBeam/Mac type battery packs that use the nickel strips, and most of them are several thousand bucks....with one highly recommended exception...This Sunstone single phase welder is about $1,000 but once their last two are sold, their lowest end model will be $2,200...with some improved features.
I talked to several people who have used this with Li-Ion, LiPo, NiMH, NiCd and say it works great, and with a power booster can make a double spot weld every 1/2 second. I also wanted one of these to be able to weld Li-Ion since you cannot solder them.
Some guys buy lathes.....this just seemed like a fun and useful toy. The Nickel strips work well in packs up to about 30-40 Amp draw. Beyond that soldering works better, which I also have started doing.
If anyone is thinking of getting a relatively low cost battery pack spot welder, they now have one left at this price model.