Very useful link that Swifty, I'd just assumed that a bespoke prop would be megabucks.
Did you have to provide the dimensions required and send them your own flanges?
Purpose made props at that price opens up a lot of other engine options, but finding information on weight/dimensions/ecu and fueling requirements seems to be a bit hit and miss.
Apart from the Puma and MGF engines, motors I've considered also include: Honda S2000 (too expensive); Mazda RX8 (too fragile?); BMW straigt six (too big?); and the range of Mercedes supercharged 4 pots complete with
six speed manual 'box, or maybe even their 320 V6 (dimensions anybody?).
One rather worrying development, however, is that both the alternative engined Sammios that I'm aware of - one with MX5 1.8 power and the other with a BMW 1.8 four - seem to have stalled (excuse the pun) as the Mazda one was just sold unfinished on ebay and the BMW conversion has gone very quiet after a promising start.
My thinking if I
were to build a lighter, faster, track focused Spyder would be to go with an established conversion, such as the Puma option, and buy a complete, running Puma to donate its engine, ancillarys, ecu and loom.
That's a project for two years' time though when I'll have more time and money...