hey i'd like to convert my 1200 with a new engine. could people express some ideas of something cool that wouldn't be really expensive. cheers

That depends on what you consider to be cheap.
An A14/15 is probably the most straight forward swap, and therefore the cheapest.

how much have people spent on an A15 engine conversion. i am keen on the CA but if the A15 is cheap i mite go that way

If you find a 1400 sunny in the paper with a reasonable engine and bolt it straight in, you will get the job done for whatever you pay for the engine plus a few hundred bucks if there is somthing you cant do yourself.... or it needs a clutch or whatever. Plenty of info on how to do it in the tech section

You can spend as much as you want to on an A14/A15 conversion- professional rebuild add $1200-1500.......add a cam grind, extractors, exhaust, webbers, turbo, fuel injection and things start getting silly very quickly.

If you want to do a CA conversion budget for $10-15k plus.