There are a few options that are ok. I think the one everybody knows about first is the powerups by ABUniverse though because they give you samples when you buy stuff like onesie. I like the NorthShore Booster Pads / Contoured Diaper Doublers just because they hold enough for me and are comfy. Here is their link
http://www.northshorecare.com/diapers/b ... shore.html
&& here is their soak capability
http://www.northshorecare.com/media/wys ... s/D002.jpg
Bambino diapers has got a quadro booster that is good but scented (im alergic to scents &&get rash). It says it holds 850ml which is something like 28oz so big soaking capability. here it is
https://bambinodiapers.com/quadro-booster-pads-c-6
power ups by abu are here && it says they hold 900ml which is like 30 oz
https://us.abuniverse.com/product/abu-power-ups/
some people do this where they buy a baby diaper and cut off the wings and layer it......not a bad idea!!
I know somebody who buys the Depends Guards for men and uses them to double and they say they are really comfy really good feeling but not great absorbency for soaking so it dont make the diap last extra long time but maybe an extra wet or something
https://www.walmart.com/ip/Depend-Incon ... t/16940253
I read of some body that liked the Tranquility TopLiner Contour Booster Pads and they can hold up to 28oz it looks like but northshore rates them lower than theirs
http://www.northshorecare.com/diapers/b ... ntour.html
TotalDry makes one boost up ultimate that says it will absorb quick 1,700ml and that's just crazy amazing
https://bambinodiapers.com/totaldry-ultimate-boost-ups
The attends and tena and depends and the pads for incontinence you see in the stores can be used decent usually if you slit the back so that the it will keep soaking on down into your diaper and not run off the back or front instead when its full to brim
If your trying to be cheap then this is probably your BEST bet to go because you can take 2 of those cheapy store bought pads for urinary leaks and slit the backs and then layer them in your diaper
if you want it real thick and you find one you want but you wish its thicker then just keep layering