Hi,
I'm not an Auster owner myself but I do have to say that an Auster is not a particularly cheap aircraft to own and operate. Only a very few are on a PFA permit, most are still on a full C of A. Most use British In-line engines that have short TBOs and cost ca. £10k to overhaul. Other parts such as props and mags are in short supply and can be very expensive.
I've always wanted an Auster, but however I look at it I just can not justify the expense of keeping one in the air.
I do however own a 1/3 share in a Taylorcraft BC12 - Have you considered one of these? They are the original aircraft Austers were developed from. Most are on a PFA Permit and they use the cheap as chips Continental A65 Engine. They do an honest 100mph and seem to have much better ground handling than Austers. Operating costs are are simular to a J3 Cub or an Aeronca Champ (IE not much!) - just an idea...
The others will probably chime in with more hard data re costs as I know a few regular posters are owners - In fact, It may be worth PM ing Low'n'Slow. He has a splended Cirrus powered example and I heard murmours that he may be looking for a change..
Cheers
Kingy