pretty much any keyboard and mouse can be used for gaming. you absolutely do not need to spend a great deal of money on a keyboard or mouse if you dont want to.
some things to look for:
-keyboards and mice with a matte finish and not a glossy finish. or else when you sweat your fingers will slip around which isnt good.
-optical mice are preferred for most users. i would say at least 800dpi but you really dont need any more than 1200dpi.
-standard sized or large sized mouse with standard 2 button, scroll wheel configuration.
-both keyboard and mouse i would suggest to be ps/2 or at least usb with a ps/2 adapter.
-full sized keyboard. personally i prefer full depth keys on mine.
-use a standard rubber/foam mousepad not some gaming pad as they arent worth the extra cash.
-buy a mouse with good teflon feet. the bigger, the better. sort of like what razer did with the to very large front and rear pads but in a cheaper product.
as far as suggestions...
cheap offerings from logitech or microsoft will often work well and for quite a few years if you take care of them.
you could also just buy a $5-10 knockoff brand of mouse or keyboard for now and then get better products when you have more cash available. it will get you through in the meantime and gameplay wont be drastically affected. you could save up for a mechanical keyboard and better mouse or perhaps a gaming logitech keyboard and razer or logitech mouse.
if you have any free dell mice and keyboards they will also work.
in general what you want is something that is comfortable for you to use. the tactile feedback and resistance of the keyboad as well as the size and overall layout should all work well for you. the size of the mouse and layout of the buttons should also work well with you.
what i would avoid are any gimmick products like the r.a.t., fold up mice or laptop mice and micro or chiclet keyed keyboards. personally i would tend to trust manufacturers like microsoft and logitech in the budget arena before i would trust newcomers but its up to you.
remember buy a mouse and keyboard for function and not aesthetics. just because it doesnt have fancy lights doesnt mean it isnt the perfect choice for you.