Hello and welcome to SubSim
I know that a lot of people had problems with Starforce, but I never had one so far. So unfortunatelly I cannot help you on that. The topic is a bit 'sencitive' and reaches the forum rules to their limit, so let's leave it here as I don't want to get the moderators involved. As far as buying SH3 I guess you can buy it on-line if you have a credit card. There are a couple of on-line shops like amazon etc that have it. Check out the prices and go for the cheaper one. Once you have SH3 make sure you patch it up to 1.4 version to sort out some of the bugs in the original game. Once you do this you can try any of the mods and supermods like NYGM, Grey Wolves (GW) and the pending GWX (Grey Wolves Expansion). These supermods do take the game to a totally different level. After you have a shot at them you will never play the stock game again
Good Luck