Salmon is not a "red meat." The red color in salmon is caused from high levels of myoglobin and give off the pigment astaxanthin, which is also present in the outer shells of lobsters, crab, and shrimp.
To answer your question though, if red meat/beef is too expensive for ya, then you may find that fish species such as that of salmon may be too pricey also. Some fish get pretty damn expensive. Tuna may be an alternative to that of salmon since it is usually bought at a considerable lower price. The addition of the omega fat content is a real bonus in salmon, but if protein is what you are looking for, and if beef is not an option, then the tuna would be fine. All in all, I probably agree with Mr. X and think that beef will be the better choice.
MR. BMJ