Soldato
Personally, i would strongly recommend Bilstein B6 Sports as a PRHT OEM replacement given the issues with Mazda's own Bilstein's, ie - it's a Mazda designed shock built by Bilstein that has a known weeping fault (both Mazda and Bilstein wouldn't comment if they had fixed the design when i emailed them), only Mazda stock them and they charge accordingly.
I only know this as i went through the whole rigmarole with my PRHT a few years back (had weeping all around) and after a few weeks, chatting to a load of other PRHT owners and a few MX5 specialists, they all pointed me towards the B6's which offer near-enough the same ride height (i think there's a mm in it on the back) yet feel exactly the same but are only ~£100 a corner and not the ~£320+VAT Mazda wanted to charge me.
As @Janesy B says, once you get over £6/700, you're in the coilover game and £1000+ gets you a pretty decent set of them.
Bilstein's with the Eibach springs is the usual setup if you're not wanting to go down the coilover route, which results in a 30mm drop. Pair it with a really good alignment (ie - not Mazda's standard setup which isn't great) and it'll be a great setup for road use.
Have you got any links to the OEM weeping issue that you were talking about? I've been fairly active on the mx5/Miata forums for a fair few years and haven't seen anything relating to a known problem, though to be honest I didn't try to find out if there was one.
My order is yet to be dispatched because a few parts are on backorder, so I could probably cancel.