Sounds like you have a well thought out upgrade path and have done some research. Congratulations on using some of those research skills that got you to college! If you think you might like to try tubes you may want to consider one of the Jolida integrated amps (the JD-202 is a great place to start). THey hold their value fairly well if you want to upgrade in the future and simplify/consolidate the system. Plus with all of the different EL34 tubes available and mods you can stay very bussy tweaking within a tight budget. As for CD players you can get lots of good stuff in the $300-500 range. Find a dealer that will let you take the stuff home before you buy it. The only way you'll know is by listening in your room with your speakers.
Good luck and happy hunting!
Good luck and happy hunting!