On a budget ...
The best plan for dust collection is.
1. At source, as close to the workpiece, sander, table saw or tool as possible.
2. Secondary. That's the room filter, usually suspended from the shop roof collecting and recycling air taking out the harmful dusts in the act..
3. Last.. PPE. Should be the last line of defence, make sure you have a suitable dust and fume mask to take out the harmful stuff that you are using in the shop.. Although many use this as a first line of defence and only use face masks.
The best form of masks are the air fed type that are giving a constant stream of filtered air to you mask.
Basically You are best to have the largest vacuum unit you can afford..followed by a PPE mask. Again the best you can afford..
The vacuums unit will take out all the fine particles (PM10's) with the built in filter bag or cartridge.
It would be best to have one that has got a 4" inlet and fit the head as close to your workpiece with the pipework as short as possible.. backed up with PPE.
see the link below of Bill Pentz who in my opinion has done so much reasearch and is still groundbreaking in many areas.
Dust Collection Research - Beginner's Corner
Hope you find the above info helpful.