I’ve resisted buying a $450 putter until i was sure this was a long term thing. If you look hard enough on other forums, bobby grace putters are the most talked about and land in that price category. Honestly, any belly/long putter would work and you can either do the ebay thing and find a cheap one or just find a lower cost newer one to start. I haven’t tried the holloway putters but they get mentioned and are relatively cheap (https://holloways.homestead.com/long.html).
Having gone down this rabbit hole, the equipment rule that is most relevant is that putter shafts need to be 10 degrees or more off vertical. Some SS / face on people want to hold the shaft completely vertical so you have to get more specialized in the putter that tries to skirt the rules but still putt-able being held vertically (see the GP putter for instance). I started playing around with a pure vertical stroke but found holding the putter at “normal” 10 degree angle works just as well for me, so hence any belly putter could work.
The second criteria is loft – you tend to hit up on the ball more so many people recommend a 0 or close to 0 loft. That’s especially true if you try to hold the putter vertically so the loft gets putt at an angle you will naturally push your putt offline.
The third is the longer length – I don’t think you would find much long term luck putting SS with a 34" putter. Standing more upright and having your top hand act as a pendulum is pretty important. The rules state you need both feet on one side and you can’t anchor the putter to your body or anchor your forearm, but it’s perfectly legal to hold your top hand still during the stroke and use your other hand to direct the club.
The fourth criteria is weight – i think it’s easier to putt with a heavier putter. If I were hunting for my first SS putter, I’d make sure it was a 400g head or heavier. Maybe it’s a just personal preference of mine but it seems to be true of others who putt SS.
TL;DR - i’d recommend buying something cheap to start to try it out.
For me, it’s improved my putting significantly but it does take a bit of time to get distance control right. At this point, I’d never go back unless there is a new rule change to forbid it but I don’t think that it is likely to happen. I definitely make more short putts and my lag putting is better than ever (but I’ve been really focused on lag putting per the DECADE app so a lot of it just plain practicing it more). I’m pretty picky about changes like this so I spent the first 2 weeks doing circle drills from 5’ both traditional and SS and found my make rate went up quite a bit which gave me confidence that a longer trial period was warranted. I found for myself that I putted more “on line” but that my notion of how much break was required changed because I wasn’t compensating subconsciously anymore.
Some of it is personal to me – i’m naturally left handed and play golf right handed so being left eye dominant i think makes traditional putting harder. I putt SS left-handed which makes me even more of an outlier. I also get handsy with my putting and SS makes pushes/pulls less of a problem.