I don't understand... are you asking whether it's more important to buy plants, or buy a pH testing kit?
pH testing kits are not very useful. It's nice to know what your pH is, but in the end, it doesn't really matter anyway, so you'd be better off buying the plants if you are on a budget.
pH is not as important as shops say it is. When they say your pH is wrong, what they really mean is "We don't know what's wrong so we are going to try to sell you something anyway" and then people get sold pH modifying solutions, which are useless. The most important tests are ammonia and nitrite, because these are most harmful to your fish. Sadly, they don't work very well in strip form and if you buy test strips they will be inaccurate. You need test solutions (liquid) for those.
Dan the man is wrong. 7.6 is not "very alkaline" pH, it's pretty normal. Most tap water has calcium in it and calcium raises the pH. My tap water is between 8.0 and 8.3 and yet all my fish are fine. If you try to modify your pH manually using solutions you are more likely to hurt your fish. Almost any fish can be adapted to any pH level. It is really not a big deal. Go for the plants. Ignore pH for the most part.