Heres a cheap light option for you
http://www.ebay.com/itm/24-48w-T5-H...119?pt=LH_DefaultDomain_0&hash=item2578cf244f
Heres another brand that includes bulbs for a little more
http://www.ebay.com/itm/24-Dual-PRO...763?pt=LH_DefaultDomain_0&hash=item460c9f8d83
No, they are not the best, but they are better then what your running and are not expensive by any means compared to most of the other things in the hobby. Honestly if your working with that small of a budget you should of waited to start but we have all been there before
And now there is no going back.
I would defiantly upgrade the lights, Not sure what your filtration method is, but try running some AC (activated carbon) as well as change out 50% of the water.
Salinity or tempurature could also be to blame, its one thing to test them, its another to have your testing equipment calibrated.
For the hydromiter, make sure to always rinse with RO/DI water before and after using, take a test of your water. Record the reading, then take a sample to your LFS and ask them to check it (should do it for free with a Refractometer) You can then compare the ratings and know how far off your meter is (they are ALWAYS off, usually by a little, but i have seen .5 points+ out of the box.
For the heater/thermometer. First if you dont have one, get a thermometer to stick in to make sure the heater is working correctly. Then take a tall glass, fill 3/4 of the way with ice then the rest with water. Wait until about its about 50/50 of a mixture and then put in the thermometer. This will cause the water to be at exactly freezing, and allows you to see how far off it is, and adjust the tank accordingly. You will also find the temperature settings on most heaters is incorrect, and just compare with a calibrated thermometer to know how to adjust.
If anything is off by a lot, don't change it all at once, go half way and wait 12-24 hours and then the rest of the way. Fluctuation is worse than high or low levels.
If that does not work, i would then go the parasite route. Because anything that could have been there should have been effected by the dip, and it would not cause all of them to close up. Some opened up after the dip most likely because there "slime caps" popped off, and they were able to open again. I believe someone already mentioned lightly cleaning all them off with a soft brush, personally i just use my hands and also shake them around in the water and move them around in the high flow areas to clean them all out once and a while