Our computer originally came with 128 MB of RAM for Windows Me. Then my dad installed another 256 MB.
That totals up to about 384 MB of RAM.
Are RAM sticks cheap, especially the 256 MB ones? Or what about 1 GB or even 512 MB? Why are they computer model specific?
Yes, most RAM is very cheap
Just by the low number I am guessing you have PC-3200 or less DDR SDRAM. But only way to know is to check.
RAM is rarely model specific. It's only the big manufacturers that add in extra bits so that you have to buy their RAM - so that they can bump up the prices.