I would recommend putting up the biggest thing you can afford that will not get your lease canceled. If the Diamond X-50 fits then it will work better than most other suggestions. Comet has an equivalent with similar specs and performance.
I recently bought a Tram clone of a 17ft Comet GP-9 off Ebay real cheap and am pleased with its construction and performance at less than half what the Comet would have run. So I just ordered a Tram 1480 8ft version for another project at $58 with free shipping. There are lots of antennas to choose from but the Tram 1480 will run circles around any Ed Fong J-pole and they will run five or six circles around the COMPACtenna thing, which I also have.