I've been in a similar situation, I earn around the same although being abit older (just turned 22) has helped on the insurance side of things. If you really must have the Supra and don't want to wait a year or two and can afford the car outright then I would go for it, but have a cheap run around for work/running around etc, until you can afford to run the Supra on a permanent basis, using the Supra everyday will only increase milage, devalue the car, cost more on fuel bills and increase the chances of needing replacement parts.
Some insurance companies let you insure another vehicle temporarily, I can get my Supra (UK thankfully ) insured for £25 a day if need be, or £1200 a year. I also have a saxo VTS which I use for work etc, paying £500 a year to insure the saxo and can easily afford to run both, and also modify the Supra each month this way.
I would find a nice example, be prepared to spend abit more for a mint condition Supra, sell the punto and get a reliable cheap car to run around in, why does it matter what car you use to get around in when you know you've got a nice shiny Supra sitting at home to drive at will?
You should make money off the punto which can be kept aside if the Supra happens to need any repair work, and plus you've still got a vehicle to get around in which will allow you to afford to repair/modify/run the Supra, if you can insure the Supra on the temporary scheme to use only weekends/special occasions it would be ideal to keep initial costs down too, although will work out more expensive if you intend to use the Supra regularly
It's the route I've taken and within a few months it will have allowed me to have my dream Supra, I'll soon be selling the saxo VTS and getting a cheaper runaround too which will allow me to run the Supra more