When deciding on your options, just be aware that many of these lower end discount dust collectors tend to have very poor filtration and have limited airflow and static pressure to work with (in some cases the CFM specs are taken direct at the inlet with no waste bag attached on the exhaust, so it’s sometimes difficult to know how much faith to have in them — but regardless actual airflow will be far less at the end of a 10ft hose). They all tend to use filter bags with a rather large weave (that pass a lot of the more harmful fines) because anything better (finer) would significantly reduce the airflow of such a small impeller and motor unless the bag were many times larger (more surface area to offset the restriction of a finer mesh).
So they can be effective with very short runs of hose (direct to tool) when it comes to collecting the larger chips and dust. However, the fine dust that tends to remain suspended in shop air and then settles out onto everything will tend to pass straight through the bag and into the shop air. They clean up the visible mess well, but the unhealthy fines that get into our lungs and settle out in paint jobs and on all flat surfaces will very much remain so it’s best to use them in a shop that has good ventilation to the outdoors.
I could not find any specs listed on the bag filtration level — ideally you want 1-2 micron (the lower this number the better), but it is almost certainly considerably coarser (likely in the 10s of microns). Also, 12 gallons sounds like a lot of capacity until you realize that as the bag fills their airflow decreases (further reducing effectiveness) so you never want to really fill the bag and if you have ever jointed or thickness planed a wide board, even 12 gallons goes by very, very, quickly!
But if you have good shop ventilation, or work outdoors, then as long as your expectations are realistic then they can have some utility. It is also worth noting that some operations, like jointing and planing, don’t necessarily generate a lot of fine dust in the first place and are, thus, less of a concern (though routing, sawing, and sanding do typically generate a lot of fines).
When it comes to collecting sanding fines, however, your best bet is the lowly shop vac coupled with an upgraded HEPA filter as they excel at that job — they also work great for hand routing with routers that incorporate integrated dust collection — and the much higher static pressures they develop allow you to maintain respectable airflow to the tool despite the typically narrow hoses most sanding tools are designed to accommodate.
