I also am a DR Highbeams user, and I haven't found any that are real cheap either.
www.bassguitarstrings.us is where I've been getting mine because the guy that runs the place has treated me real good. There are one or two I've found that have been a little cheaper, but not enough cheaper to pull me away from this guys place. I also would like to buy them cheaper, but DR's are so great I hate to buy others, just to keep the business going DR's way, and keep some of the cash here in the US. I like the fact that they are at least one the last things still made here.