Jessie's advice is solid. I'd put your money into a used body and lens or lenses. If the body is for tank shooting primarily, I'd read up on white balancing. How you like your body for tank shooting is going to hinge on your ability to get close to correct WB right out of the body, with tweaking in PP, as opposed to major adjustments in post. I've never been able to get closer on my 7d than using the 10k colour specific WB setting, compared to custom setting WB, but it is close enough and the rest is done using Lightroom. As for lenses, there are so many options, zoom vs prime, macro etc. I'd get a zoom kit type lens with 18 mm on the low end of the focal range, learn on that, then get an entry level macro used such as tamron 90 mm which should be in the $350 range.