You can get it back in a few days. Go straight to a high security high intensity resource extraction site. Help the feds to kill the wanted guys. That'll get you 1 million an hour, so iafter three hours, buy a Cobra fitted out for long range hauling. Go down tp Ceos and rank up doing all the Ceos/Sothis data missions. When ranked up, take a couple of the long range hauling missions back to the bubble. By that time, you should have 22 million for an Asp. Go back to Ceos and do the data circuit and take all the long range hauling missions with a ratio of around 1 million per 4 tons. Bring them back to the bubble. Repeat one more time and you should have enough for a Python. 2 or 3 laps should get you your Anaconda, as you make about 50 million per trip. That's about a week of evenings. In fact tests have shown that it takes about 15 playing hours from start if you do it right.
I guess it's too late now, but for anybody else, your rebuy is bumped up when you upgrade modules. when it comes to the rebuy, you can untick the modules to go back to the basic ship. You only need 7.35 million to buy back a basic Anaconda. Your typical 300 million upgraded one would cost 15 million.