^ What Ash said plus
this is a good starting point :
http://www.mx5mad.com/begisturbo.php
more on it (plus price in $)
http://www.bellengineering.net/Pages/pr ... BEGiS.html
There is also the option of the GReddy kit with a 1.8 turbo manifold
1.8 Manifold can be bought here :
http://jgsturbo.com/mx5bp.html
GReddy kit from many sources, the exchange rates will really work in your favour at the mo' (Fergus, where did you pick yours up from?) so you should be able to pick one up NEW for around 1000e.
Am v.happy with my GReddy, it works well (lots of fun, will give you a spin the next time we meet) and has been quite reliable.
Kits from
www.Flyinmiata.com are above your budget I'm afraid..
If I was doing it again, I'd DIY it and buy all the bits seperately. Speaking of which.. I may know of a GReddy turbo for sale if you are interested..
Then pick up the manifold linked above, oil lines, boost guage, a downpipe from ebay and you could run it at 6psi straight away.
Steve