By road is always a best way to reach Goa as u can see the scenic beauty. If u want to opt for train then catch from Kollhpur go by road till Kollapur by GaganBavda route
If you don't mind the long drive which can get a little hectic, self transport is cheaper than Public transport. but if you are two drivers, you can give it a try
A road trip to goa from Pune or Mumbai is always a good option. You can also have a stopover at Amboli which is beautiful. It will give you a break from the driving too.
Pune to Goa by road will be convinient. If you are traveling with family then it is cost effective too. Also, when in Goa if you are planning to visit North and South Goa both then your own car is the best as taxi drivers will charge you around 3 to 4k from North to South Goa. In 10 hrs you can reach goa via route Pune-satara-kolhapur-amboli-baga via NH 48
Totally depends on how many people are travelling..if two to three or more then self will be cheaper plus added advantage you can enjoy the scenic views by taking a halt wherever you want