Lens or Camera upgrade (or both) advice needed

[peggary]

I use a Canon Rebel 2Ti and a Canon 50mm f/2.5 compact macro lens, with a Manfrotto tripod, center pole inverted, on a tabletop in outdoor natural light.  My camera points directly downward to capture an approx. 1.5x2" area of a relatively flat surface.  (1) what Canon product, lens or camera, do I need to improve my ability to capture an even smaller area, or the same area with greater clarity to allow me to crop to a smaller area, and still enlarge to produce, at a minimum, a excellent 13x19" print  (2) same question with the goal of a sharp 2x3' print and (3) if your recommendation is for both camera & lens upgrade, and I can only afford one, which would get me closer to my goal, for my buck?  

[peggary]

I appreciate the advice from you and everyone.   I'm a hobbyist  photographing a small area (1 1/2 x 2") of rocks, with 1:1 magnification.  I use photoshop and have a new pixma pro-300 printer, but my camera is 10 years old with 18 megapixels and my lens is 13 years old.    I'd like to capture even smaller areas with sharp detail and enlargement capability to at least 13x19", but preferable more.  The advice I received gives me good direction for my research into new gear and your advice on the future of DSLR adds to it!  Thank you.