Some Question about reef equipment

[pangking]

Newbie, visited couple LFS, getting confusesed:

1. 120GAL ( 2X2X4 ) reef ready class tank will cost 750.00(brand name)-350.00(no name)

2. Wood stand for 120 GAL will cost $1000.00-$350.00

3. Lights $1500.00 - $350.00

4. A 33 GAL cheap glass tank + a filter sock = sump ?
(A guy showed me a really simple sump build with a filter sock + skimmer in a glass tank, no any partition, ran as a sump)

So I just don't sure if I should spend 1500.00 for the light ? and any stuff that above more expensive are better or necessary ? and a pre-made sump($400.00) or just a glass tank?

Should it cost $4000-$5000 to build a 120 GAL reef tank?
Thanks for any words!