Welcome to Gundam Models....your piggy bank will so not like you now =P
I only buy Gundams online these days and usually it's from Hobbywave.com or HLJ.
As far as a starting point, that really depends on you and your comfort level. HGs might be a good starting point depending on your model kit building experience. Go for something simple so you can get comfortable and then go from there. The older MGs are bit easier than the newer ones.
As far as paint goes, you can find lots of translations online these days but I would recommend
www.mech9.com as his translations tend to be pretty close. As far as brands of paint, Mr. Hobby Color will usually match with what is in the instructions but I find lacquer based paints to be difficult to use. Tamiya is another good option and with their acrylics, if you make a mistake you can clean it off and start again. I wish Aqueous Hobby Color was still around in the North American market though, as that paint was awesome to work with.
Good luck =)