Depends on whether you're buying within the EU (VAT accounted for) or importing from further afield.
If the former, then prices tend to be higher, even accounting for the VAT, than they retail in Japan, with their 8% VAT rate included.
If the latter, then you can expect to pay a good bit less.
With so many models available (not all still produced) there's no exact price, but if we take the new SBGV005/7 models, they can be had for around the £1350 mark, plus other costs of acquiring and postage, before sticking 20% on when it lands, and Parcelforce's £15 for admin.
Older models can be had for around £800 plus the above, although there's been the odd few which were already imported, so no costs above postage from whichever EU country the seller was in.
Bear in mind that apart from the models mentioned, the majority of GS quartzes tend to be 36-38mm. If you want 40mm or above, then you've only those two, and most of the Spring Drive ones to consider. The autos, inc the hi-beats, are 38-39mm, typically.
If you're planning on self-importing, and quartz is the primary option due to financial constraints, then don't turn a blind eye to the Citizen Chronomaster range or The Citizen range, but again, they're typical Japanese size – 37mm, iirc – but have a 10 yr warranty.