If its a cheapy vac you're after then one of those b&q mac all lister vacs would do, not brilliant but they work, are cheap and you can buy the spares from any b&q.
If you're looking for something more substantial and professional but still portable then a tv50 from pwm sales is a good option. If you're doing lots of dust collection, stick a pre-separator onto it, makes loads of difference.
Forget numatic for fine dust collection long term, their filters can not handle it.