First off Geordiedod, which model? There are several, mostly distinguished by having single speed only, or variable speed. There are other differences between models too.
2nd, any idea of it's age and condition?
3rdly, speaking VERY generally, depending on age and condition, a very rough rule of thumb is that any S/H item will attract about 50 to 60% of it's new price - though CAUTION please, many times other factors come into play beyond that simple calculation - e.g.'s are how much someone wants something; is the item still in production; is it especially rare; how far apart are buyer and seller.
In the case of Hegner scroll saws, they generally have a good reputation, and are still very much in production. I'm NOT based in UK, but very roughly, new prices for Hegner saws range from about 500 quid plus to over a 1000. Note please that I'm NOT based in UK so my info is not exactly up to date.
In short mate, more info (and ideally a few pix) are needed before someone with more up to date info comes along to answer your Q.
Thanks AES the reason I ask is I have tried a cheap saw and it didnt last long. Looking through this forum I see many people have been through this including some expensive saws too. I'm not to sure if I need different speeds I just need a reliable work horse that wont need repaired too often.
Well then, I GUESS you could work on the basis of "only" needing the smallest/most basic models of Hegner saws - they certainly do have a very good reputation and are often referred to as the Rolls-Royce of scroll saws.
As said in my last, you'll need to check on current new prices and go from there in deciding what you want to pay. Just look on the obvious places like ebay and gumtree, etc, for current and recent sale prices, plus check with an "independent" tool seller (e.g. Axminster), plus with Hegner UK themselves for current new prices.
As said, I don't live in UK, sorry.
From all I've heard, you certainly won't go wrong when buying Hegner, but about 5 years ago when I had the chance to actually try a new multi-speed Hegner and an Excalibur side by side, although I thought the Hegner was actually the (slightly) better built of the 2, I actually chose the Excali.
But that's another story, and since then it appears that Axminster have produced a "cheapened" version of the Excalibur and several members have had problems with those.
As said, you certainly won't go wrong with Hegner. Good luck.
Edit for P.S. I THINK (don't know) that multi-speed is "just one of those things" - once you've had it you wouldn't be without it, but if you've never had it you don't miss it! Certainly I wouldn't be without it but that's me, AND I do a lot of stuff on my Excali that most people wouldn't regard as "proper" scrolling.
I can't help with price as I was given my Hegner. It is variable speed and I would not want to be without that function but I guess it depends in what you use it for. In my case it was used for cutting intricate shapes in abalone and mother of pearl that I use for inlays.
I bought a second hand Hegner (multispeed), which, at £51 was a real bargain, no issues with it, but I use pinless blades as fitting the pin blades I find a real faff. You can see what Hegners have sold for if you used the advanced option on ebay search and tick sold.