Im 87kg, wear a 5mm wettie, and started with 5 x 1.5kg weights on my belt. To stay horizontal I had to keep kicking and paddling awkwardly. My back was killing after 2 hours.
Bought this Sporasub quick release weight vest for $55 to solve the problem
http://divein2scuba.com/index.php?_a=vi ... uctId=2499The brand name lead weights cost $22 each but I managed to find some on ebay
http://www.ebay.com.au/itm/380430065974 They cost $31 incl delivery for a set of 4, which is a lot cheaper than paying $88 for the brand name ones. They don't look as good, but who cares. And for those that do care about looks... they are hidden in vest pockets anyway.
If the seller doesn't have any of these weights listed on ebay just send him a message. Here is his ebay store. I think he also sells 1kg lead blocks aswell.
http://stores.ebay.com.au/ortho562006The vest and lead cost me $83. Unless you buy 2nd hand I think you'll have a hard time beating that price.
Now I use 5 x 1.5kg on my belt plus 4 x 500g weights in vest. It seems to do the job.
By the way, watching you float to the surface and then get flipped onto your back because of the weights would be funny to watch.