I swim in a pool mostly - no suit novice. I enjoy staying under water and need advice on how to stay there without my wife having to stand in the small of my back. If I buy a web belt, what would it cost to furnish it with the lace thru style weights - how many and cost of each. I am near 200#, so I figure 20#'s of weights. I can't tell from your ad, what each weight costs?
Weighting requirements to achieve neutral buoyancy (neither "floaty" or "sinky") vary widely from person to person (because of body mass index - not just weight and height), the salinity of the water, and the gear/suit you are wearing. Assuming from the above that you are in a freshwater pool and without a wetsuit, neutral buoyancy is usually achieved with a pair of 2 pound weights (one on each hip) or so.
Some take a pair of 3 pounders or 4 pounders... Or wear four two-pound weights (two on each hip). It all depends on all of the above factors.
Your natural buoyancy will even change with the size of the breath you're holding... A larger breath will make you more buoyant ("floaty") and will require more weight to be neutrally buoyant.
Beware of TOO MUCH weight... Your suggestion of 20 pounds, for example, would firmly anchor you to the bottom of the pool, and without fins I am confident that you would not be able to reach the surface for your next breath!
The bottom line about all of this is... It depends. But start light and add weight until you're happy with your weighting. Also learn how to ditch the belt quickly underwater in case you have too much weight and need to get off the bottom to breathe. Its also a good idea to try all of this in the shallow end before progressing to the deep end!
I have no idea what your BMI is, or where to start you in terms of weighting... But a good place would probably be with a pair of 2 pound weights on a length of webbing with a buckle. You're properly weighted when a half breath floats you at eye level (assuming you're vertical in the water at the surface) with no swimming or sculling at all. A full breath, then, would make you slightly buoyant while a small breath would make you slightly negative ("sinky").