Probably the best low cost option is a vacuum attachment on a knee strap. A good system allows you to increase or decrease tension easily and is comfortable and discreet. There are taping methods that allow for all day use without having to re-tape every bathroom break. And if, for some reason there is a system failure, the components are attached to your knee so at least they won’t fall on the floor.
The Phallosan forte is marketed as a stealth ADS that uses a belt attachment. It’s costlier but you might check that one out.
There are lots of knock-offs, generic versions and variations of these kinds of systems.
Some people use noose or vacuum attachment frame extenders under their pants but honestly I don’t know how they function with them and feel confident that they are stealthy.
Others use ring-shaped weights on the penis but my experience with those is that they cause a lot of swinging while walking, so not exactly discreet. Some people have wrapping methods that propose to keep them in you pants if there is a system failure, but I haven’t really gotten that to work 100% so the possibility of a ring-shaped weight falling out of your pants leg and thumping the floor in front of your boss is enough to strike that method off my list.
Any work-safe option is probably going to be low tension/ long duration, since most people can’t find privacy and reset every 30-60 minutes. Some people have had good results with low tension/long duration as a primary method while others prefer to use it as a method of keeping ongoing tension after a more intense method of stretching, like manual stretches or hanging.
In any case I’d definitely get super confident about any system at home in privacy before venturing out to work with one. Definitely don’t want to trouble shoot it in front of coworkers or clients/ patients.