I tried just about everything. Anytime I found myself in a green side bunker and there was no lip - I'd use my putter 90% of the time. And that worked out okay about 40% of the time, although I seldom got the ball close enough to the hole to 1-putt. My goal was to simply get the ball out of the bunker and somewhere on the green. Of course, very few courses I normally played had those shallow bunkers without much of a lip.
I bought specialty wedges, the kind you see on Golf Channel infomercials where the "12" handicapper suddenly turns into Phil Mickelson from the sand. But they never seemed to work for me. Not because the design of the club was flawed, but rather my technique. The interesting thing (to me) was that when there were no bunkers in play on a handful of greens that I would hit approach shots into each round - I usually found the heart of the green without problem. But the ones that did have them (and it could be with short iron approaches, even) my objective went from hitting the green to avoiding the bunker at all costs.
I'd shot several rounds below-par, yet from a green side bunker - guys who I played with regularly and who often struggled to shoot in the 80's - they still had a more competent sand game than I did!
I bit the bullet and took a bag of shag balls out to a green the furthest point away from the course one evening. I simply couldn't continue letting my woeful sand game ruin an otherwise decent scoring round. I spent an hour hitting shots from fluffy sand one evening, and started getting the hang of it. I wasn't getting them into tap-in range, but I did finally develop enough feel to get them to within 10-15 feet from the hole. And with continued practice for a few weeks, I started judging the distance incredibly better. That 10-15 feet would improve to 8-12 feet. More practice would give me even better results.
And too, after I became reasonably proficient from regular fluffy sand - I began practicing in bunkers with less sand. That was definitely much more difficult, but eventually I learned that a lower-bounced wedge with a bit more of an aggressive swing in those bunkers with less sand gave me acceptable results, all things considered.
Maybe I'm different... but for me, it took getting out a few evenings each week and figuring out what worked and what didn't. No lie - my GIR% increased, and all because I no longer feared finding a bunker. My sand game actually went from being a glaring liability that was costing me several strokes per round to becoming a strength in my game.
If you learn the basic technique, it just simply comes down to a little practice to keep it in good stead. But it will take a time investment initially. After that - not so much.
I think the natural tendency for many golfers is to avoid practicing the things they struggle with. And I understand it, I was the same way. And even today - I would rather work on my tee game and shorter irons versus longer irons and hybrids. But that's really the only secret to improvement. The golf equipment industry has made most of its money on the false hope of weekend warriors, that they can sell them that one club that they simply cannot mishit. They're in the business of selling equipment, not technique.
Good luck! Hope you find something that works, because I'm familiar with that frustration!