You could potentially do an amazing planted tank for around $600. A build my LED
light fixture will run you about $250, Pressurized CO2
$150 ish, Tank $100 ish used, PFS Substrate $20 - $30, ferts - $20 Then you only have to find a heater and filter that you like.
That doesn't leave much left over for stocking but that is something that can be done over time. It will also be SUBSTANTIALLY less than a saltwater tank the same size.
A school of neon tetras and another school of harlequin rasboras will give you lots of reds, blues, and greens from the plants which is quite a bit of color.
If you are still set on a saltwater tank I would suggest going with a smaller tank in the 20g range with a 10g refugium.