One can find and purchase second hand Nintendo DS and games for sale on websites such as Amazon and eBay. They are also available on Preloved and Free Ads.
It is difficult to give you specific locations as to where you can find cheap prices on old computer parts, but there are a few options available. You will likely be able to find what you are looking for on sites such as Ebay or Amazon.
You find it on your walks and sometimes you see them in the second hand shop.
craigslist, ebay, or a second hand store
Nintendo GBA's are no longer produced so the only place to find them are at second hand shops. There are several online resell stores that sell them like ebay or amazon.
You probably won't be able to find it in a shop, unless they sell second-hand consoles. You should be able to find them in internet shops such as Amazon or eBay.
eBay or craigslist. Happy hunting
Some sellers do.
flee markets, pawn shops, and second hand stores.
One can get a second hand Nintendo 64 system in the UK from a store named GAME. The GAME store can be found in most towns. They sell many used games consoles nationwide.
ebay, craigslist, used game store, goodwill, second hand store
This Nintendo DS Lite was a Limited Edition in the Ice Blue colour. One may find a second hand one on eBay or Amazon. Alternatively one can visit the Nintendo website regularly to see if an additional amount of DS Lites in this colour are released.
A new Compaq Presario M2000 is very difficult to find since they were manufactured from 2000 to 2005. You may be able to find a used one from a computer shop that sells second hand computers.