How good are you with electronics?  If you're familiar with soldering you can easily build your own with a kit such as this one.  It will outperform preamps costing much more.  It's built around a good opamp, and I've had great results with it.  It doesn't come with its own power supply, so you'll either have to use two 9-volt batteries, two ac wall adapters (preferably regulated ones), or ideally a regulated power supply kit (also sold on the same website).

Another advantage with such a kit, and one I really liked, is that for b&o turntables, you can put the circuit inside a nice looking aluminum enclosure, and put DIN plugs on it so you can plug the turntable in directly without any adapters.  I'll dig mine out and take a picture.

If you don't want to build your own, I'd recommend a pretty inexpensive one.  You likely won't get much better sound as you go up in price.  The sound may be a tad 'different', but that's not necessarily the same as 'better'.  This is a pretty common one in the US.

Art DJPre-II Riaa Premap

Although I'd recommend an inexpensive one, I'd still go with a basic brand though.  On that cheap black box one you don't know anything about the circuit or power supply.   You don't necessarily know for a branded one either, but I'd bet it's more likely to be designed correctly.

Austin

At £14.99 it's worth a try!

I use a similarly priced one and it's fine. Looks similar to the one on ebay but has no name to identify it. I have supplied similar to customers and nobody has ever complained.

Make sure that you maintain ground continuity between the deck and your amp or you will get mains humm!

This one is fantastic!!! (Not just because i'm selling it👍)

I'm sure it is!

And what about the solution Profitec TC400? It sounds good?

Thanks for your help! 

I have ordered a Cambridge audio RIIA. Costs around 60 Euro. Will arrive next week and then I can tell if it is any good. Not all cheaper ones I have checked has ground connection which I have found trouble with.

I've recently bought a Graham Slee Gram Amp Bridge.  Looks well made (In the UK too) nice little black aluminium box.  So far the sound is really good, really brings the base out compared to the cheaper one I was using.  Now just waiting for my SMMC2 that I ordered a month ago from SoundSmith!

Pete.