well here's the thing....
it depends on what kind of fish you want to get. if you are going to get huge fish, then yes, this is not the tank for it.
for one betta, i would think it's a great tank.
cost is relative with what you are comfortable spending.
for the baby biOrb, a 4 gal tank, that comes with everything you need right off the bat, $59 wasn't a bad price for me. comes with your filter, cleaning pad, chemicals, food, biological media, tank light, air pump, lid. all you do is supply water and fish. the clean up is easy too and i wanted something different rather than a rectangular tank. asthetically, it is very pleasing to me which is why i opted for them.
so for smaller fish, where you are not going to keep a huge community tank nor bottom-feeders as this tank is not suitable for them, i would highly recommend it if it is in your budget.
plus you have a company that stands behind their products.