You may get by with them, however don't expect your parameters to test out accurately. I don't have any experience with the red sea brand, however my first test kit was the one I could "afford" and I'm not pleased with my test outcomes. When you test your water, get the first two or three tests double checked by your LFS, as this will determine the accuracy of your kit.
I personally think those red sea test are not worth a dime, I used them for a couple of months and they are way off IMO. If you cannot afford Salifert, then look at the sea test and fast test kits, and get salifert for pH, alk, and Ca.
I also think Red Sea tests stink. I still use the ammonia and nitrites tests because I still have them but Salifert is the way to go IMO... the Salifert alk, ca and mag are really nice tests IMO.
I've used Red Sea and it sucks. The only thing it's pretty accurate on is Ph, but everything else sucks. If you don't have the money to spend on a Salifert, get a Fastest kit, but it'll still be more expensive than Red Sea. Trust me, it's not worth it.
Yet another vote for FasTest. Expensive up front ($50 for the master kit which will do pH, ammonia, nitrite, and nitrate) but cheap to refill (ex. $8 for the pH refill). Accurate and reliable enough.
But for Ca and Alk, IMO there is no substitute for Salifert.
looks like I will be buying Salifert!! thanks for the info everyone. They shouldn't allow some of these manufacturers to sell this stuff if it isn't reliable!
I would not buy salifert for ammonia, nitrite, or nitrate . . . no need to spend a ton of money on these tests as you will most likely hardly use them (except for nitrates maybe) once your tank is established.
pH . . . the fastest has worked great for me for a couple years now and I feel no need to buy an expensive salifert for this measure. Only for Ca and Alk.