Echoing previous posts, DJ CD players almost all have speed control. The better ones, like Darryl wrote, somehow manage to change speed without changing pitch. (This seems horrific from a hi-fi perspective, when you consider the sound processing being done, but actually works reasonably well.)
The best makes - the ones the pros use - are Pioneer (first) and Denon (second). Occasional & bedroom DJs like myself sometimes buy the cheaper Numark decks - these are OK but not of the same quality as the first two. The cheapest new deck I would consider is the Numark NDX200 @ £130 that has already been posted, but I would personally prefer a second hand Pioneer or Denon for the same money. eBay is an obvious source, but Gumtree can be good too.
Most DJ CD players, including the NDX200, are just the player - no amp or speakers. Numark do a number of units containing a couple of CD decks & mixer (important for DJ use, basically a special kind of pre-amp for DJs) but still no power amp or speakers e.g. CDMIX1. So, they are not really a replacement for a ghetto blaster by themselves: you need to add at least one other unit and at the cheap end of the spectrum this would be some kind of combined rugged amp/speaker.
Hope this helps.
Kind regards
- Garry