My budget is around $500 a month. Basically, I need to be able to scan all listed US equities with maybe a couple seconds of delay. Ideally, I want best bid, best ask, last trade, and have this refresh once a second or less and have my program simultaneously look at a couple thousand symbols. I don't think eSignal or iqFeed will be sufficient for my purposes. I looked into NxCore, but they are extremely slow and responding to my inquiries. NxCore is also Windows only which is likely a dealbreaker for me. Does anybody know of a good feed that I can use on Linux?