Completes can be bought at a ***** or target (If your a beginner, try this, its a good idea)
Birdhouse skateboards by tony hawk and other brands have complete skateboards for about 60 so dollars. The reason these aren't used once you get good are EVERY part is made by the company of the complete. So while they might have a good deck, the trucks, hardware and wheels might be pieces of ****. However, it really doesn't matter when your learning.
Buying parts online isn't that smart as you have to pay for shipping. So I suggest you head down to your local skate shop since they will probably give you free grip (if not they're like $3.50) and put everything together. This is how to get a quality board. Most decks go for about 45-65, trucks for 35-50, wheels usually go for about 20 and if your lucky the shops will most likely include the bearings and hardware for free, but if not hardware usually costs a couple bucks and a box of bearings is anywhere from 5 to 150 bucks (if you want bones ceramics) but you should just get some decent 10 dollar bearings. That means completes usually cost 120-150 Bucks. My board is a REAL Skateboards deck (I really recommend this), Venture Trucks (Carvy, Improve pop. Good for those who are good, but might be a flaw for beginners who would fall due to the carviness), Bones Red Bearings (The Basic (everybody has them) bearings that are pretty cheap and well made), Some basic hardware, most likely SHORTY'S, the shop didn't say, and some girl wheels. When buying wheels get a 90A. 100A are the hardest wheels, which means the board wont go over rougher gravel.
I spent £450
200 pound deck
50pound bearings
30pound wheels
120 pound trucks
50 pound for bushings /grip tape /bolts / speed oil etc
$1000usd
75-130
skatewarehouse.com build complete