$1200 will get you there.
Fabricate more = less cost (AKA 'rolling your own')
Buy more finished products = more cost
That's the short answer. If you want a longer one....well...check out some of project threads; some of them are more than 25 pages long.
Sometimes the homey touches are the best but as noted above $1200 to $1500 when building your own..
Mine was around $815 with gutting and modding an old cab...(cab was 50 and totally gutted...painted, modded (extra $175)
I had a good pc so that was free... but the CP was $350..... Marquee + T-molding was $45..21" monitor $200
$225 (Cab,paint,sanding,addional wood for mount)
$350 (wood for CP,hardware (2 joys, 18 buttons,trackball, paint, overlay)
$200 (21" Acer Widescreen)
$ 45 (Custom Photoshopped marquee, 20 ft. T-molding)
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$820
(thats with buying and gutting an old cabinet, cheep yes and i happy with it HELL YES!!!)