one word--- PAINT --- it is your best frugal friend!
Look for warmer colours in paint. Off tints are really cheap and sometimes those are the darker warmer colours you could use for walls or floors.
I picked up some floor paint good to paint cement floors or patios last summer for 5$ a gallon. It was in a pinky beige tone that someone didn't like the look of.
I did my deck 3 coats (needed it) and also bought wall paint for the first room that we painted downstairs, in a warm deep taupe shade.
It has warmed it up. Chances are you won't find enough in off tints to do a whole basement so the other thing I've done, is get a 5 gallon pail which is a LOT cheaper than by the gallon, and you get it all tinted at once.
Look for golden undertones in paint, and get even the ceiling white tinted with just a drop of golden yellow for a "sunny" look. It will read as white, but have a sunshiny look to it.
Use a rental spray painter (electric pump) to do a basement unfinished ceiling to get into all the cracks and crannies quickly and easily.
-- be aware that if you do that, you need a partner with a roller coming behind you to roll out any drips, sags and runs in the paint, as the sprayer has a tendency to be thick and thin in spots due to beginner's technique. The roller will even it all out, even as the sprayer speeds you thru applying the paint. Works like a charm.
Dh and I did our rental units fast that way.
You can use it to do the whole place, ceilings, walls etc in a matter of a few hours, using the same white paint, then go back later and roller paint the walls and floors to what shade you want.
Tape off door handles, light switches, light fixtures, windows and things like laundry equipment and so forth.
Avoid painting the furnace or hot water heater, and don't spray near them. Use a roller to paint near those two as you don't want a mist of sprayed on paint to gunk up any sensitive parts.
Use Latex paint. You might need a thinned out coat of primer first thru the sprayer to coat it, but chances are you can manage with a good coat or two of ordinary latex. I've done it, and it works.
I've figured that if I need primer, to stop bleed thru, I can get a spray can of KILZ and spot prime anything that bleeds thru like kids markers or ink etc that got onto the basement walls for whatever reason. Then when the kilz dries in an hour or two, come along and hit it with the top coats of latex in the wall colour.
Once you have a basic coat or two of the warm white on everything, you can make an accent wall or two of some warm brick red or one of the tuscany sort of colours, a warm gold or terracotta shade.
The floors you can sponge on fake tiles. Benjamin Moore has instructions, although for me I prefer just plain taupe in a golden shade which is what I'm repainting my laundry room/furnace room area. It should blend with the laminate we put down there this summer which is in an oak shade.
You can also paint on a fake wood grain if you prefer. Graining tools are there in the roller section of the paint store, with instructions.
Friend of mine used varathane on raw plywood in one house, and she drew the outline of the planks with a yardstick and a sharpie felt pen, and then varathaned over that. she dotted on "nails" using the same sharpie in the places where you would expect nail holes.
It looked fantastic and it was in her laundry room, and back entry to the garage and it stood up to that kind of hard wear beautifully.
