What are ways to get more power out of a 90s-2000s S10/S10 Blazer(4.3 liter Vortec)? Cold air intakes, exhaust, engine parts etc?

Nothing much really. Chips don't do much of anything except in some case cause you to lose HP. K&N cold air intakes are BS. The factory intake is already cold air. Spark plug really do nothing but provide a spark. High end plugs and wires will get a more reliable spark, but no more HP. About the only thing you could do is to replace the engine with a fresh new motor. Especially the new 4.3L V6 that puts out more HP.

I see Lee looks through catalogs and magazines and believes all the advertising hype.

As Patrick said, there is nothing you can do, since you qualify your goals "without spending a fortune". All that snake oil crap (K&N, "cold air intakes", chips, etc.) is miraculously priced at the point most people can justify throwing their money away. You'd be better off spending that money at a casino or on lottery tickets, at least then you'd have a chance at getting something back from spending it.

Super/turbo-charging or a larger engine are your only options to make actual power, and none of those are anywhere near cheap to do right.

Good tune (plugs/wires in good shape), tire pressure at OEM spec, that's about all you can do.

Try a Turbo chip.Pretty much the same kind of chip the cops use in there vehicles,back then in the late 80's and thru the 90's.Cost ? @ $150 and up.Also update your fuel system(new after market fuel pump and fuel filter)and after market fresh air intake with K & N air filters high end spark plugs with new wires..Its a start.

Before you do anything you should install a new GM 290hp 350 available from Summitracing.com. It will end up costing about $3000 but will be very nice and it is a brand new engine, not used or rebuilt or hotrodded.