Taxi,
Start searching better lol you dont seem to be able to find anything lol
Greddy
HKS
Flyin'maita
Do bolt on kits but dont expect them to be cheap unless you buy from them 2nd hand.
Skipp123 has given you a great breakdown on what parts/injectors you can run.
Even if you build your own kit which can be done roughly about £500/600 that probably wont include your ECU that you will need then there's the mapping so expect another £500 for mapping and £300 for Megasquirt , then there's also wiring it up which costs.
Things like a couple sets of spark plugs for the tuning ,during and after.
having already played about with turbo'ing a non turbo production car I realised it costs alot more than I thought.
Also as Sturge says dont bother messing around the dipstick for a return just weld a return feed into your sump and run a line down to it much easier cost me £30.00 to do last time I took it to a welder.
No need to lower compression unless your running INSANE amounts of boost but its between 6-10 psi on a stock engine (exc Injectors etc)
Im going down the SC route and have picked up
Megasquirt1 V3
76 PIN ECU PLUG (Fits Mazda mx5 ECU harness)
Supercharger Mounts to fit Eaton M45 (BMW Mini Supercharger)
BOV (from previous Build)
Extra Throttle Body
Throttle Body mouting kit
Pulley Kit
Bypass Valve (M45)
Its still a long way off but thats cost roughly £400 ish which in my eyes is pretty good Im trying to keep the whole build including mapping under £800 quid which at the moment looks very promising as I already have a mate who has quoted me for the mapping.
But as a tip get on the MX5 forums there's loads;
Clubroadster.net
MX5 Nutz
MX5 OC
I use these as its got the US forum which is great for seeing what people are doing to there's and the tuning parts available.
I use MX5 Nutz to see whats happening in our UK mx5 scene which was my decideing factor to go SC instead of turbo again.
MX5 OC just when Im googling away questions that need answers and threads appear.
you can find out pretty much anything from Google no joke!
HTH :-)