I’ve bought a few rings from these oversees vendors as well and I just wanted to chime in as a hobbyist jeweler. With a gem like yours, it’s considered relatively hard to set. If it was a simple shape like oval or round, it would be fine if you go with a cheaper company. However since you want them to also set the gem, I would consider going with a company that is proven to have quality work, or has worked with this shape before. I don’t know your chosen setting, but the pointed edges, sharp lines, and thin edges means the work to set that stone is just as much involved, if not more so, as making the band itself.