How does one choose a phono stage.

Sometime in the future I would like to buy a seperate phono stage. Currently I am using the phono stage of my Symphonic Line La Musica integrated amp. But when I take a look at what is available is just dazzles me. There are some many brands, models and versions etc etc. Even when I limited my budget to say max $1500 there are still dozens of even hundereds I could shoose from. But before we set a budget, how do I even know how high I should make my budget. I mean my old Clearaudio basic isn't better then the build in stage of my Symphonic Line. So I should look for something of better quality, so more expensive. My turntable is a VPI Scout with Lyra Dorian cart. So even if I had the money a $5000 phono pre would be overkill.

So back to the original question, how doe one start to narrow the field. I can listen to some stages but before I need say 5 to 10 stage I would consider. So how do I narrow it down to that number.

When I think of phono stages around $1500 budget I think Nagra BPS, Whest two, Lehmann black cube with PWX, Goldenote Phono 2, Acoustech PH1, EAR 834MC, array PH3 etc etc.

So how do I narrow my search. When buying 2nd hand it become an even bigger problem, since you cannot always try before you buy. Often you have just have to buy and hope it works out.

I realy would like to buy the Nagra BPS, why? Because I like Nagra CD players, not a very sound reason but that is how it is now.

So please help me, what should I do.