If you are paying someone else to fit the springs, might be worth saving the extra for shocks to replace the 12 year old units you already have. The labour charge will be the same.
I’d recommend contacting Mike Comber at Thrussington Garage in East Goscote (Leics). He’s an MX5 specialist, and runs very successful Mk1 and Mk3 race teams, and can give you good advice on a MK3 solution, and will probably supply as well, as I know he also has (or had) a motorsports ebay parts shop.
Labour; assume £50 a corner to fit, plus £100-150 for an alignment. Mike has the full race setup equipment.