Jim,
I work for Alston & Bird in Charlotte. We do a lot of work with foreign associates. As for pricing, everyone seems pricey these days because of the increased translation costs. But, generally, my experience has been that I'd rather pay more for quality work than try to get a lower rate. If you think about it, if the quality of work is higher, the chance of second and third office actions, etc., decreases, which will in the end likely be less expensive for the client.
Regarding receiving work from foreign associates, my experience has been that if a foreign associate's practice is based principly on inbound work, they won't have a client base from which to send work back to you. Rather, work with broader (larger) firms that will have the ability to send work to you. Also, try to make a relationship at the other firm with more than just the associate(s) to whom you send work. Consider visiting the firm and give a short talk on something about US practice that they would have an interest in hearing. Getting a chance to meet with members of the foreign firm will give them a reason to want to send work your way. Also, consider that most foreign firms already have someone to whom they are sending their work, and you'll either need to wait around long enough to become that someone, or be more agressive and "casually" ask for work. It never hurts to emphasize a friendly "the next time you have outbound work, I'd appreciate if you would give me an opportunity to handle it to give you an opportunity to get to know my work."
As for what to look for, I guess a larger firm like mine has the advantage of being able to try out several foreign firms to find firms and associates we like and then spreading the word around the firm. But one quality you might not think about is the ability of the foreign firm/associate to provide quality substantive responses or suggestions rather than just being good at pushing paper. You'll probably agree with a bit of experience that the lower the rates, the more the foreign firm is just using paralegals to push your paper and not really "lawyering" your cases.
Obviously, take my comments and suggestions for what you think they are worth.
Chris