Not really too many other choices if slow connection is all you have. I'm assuming you are using dial up? I always had to find a good access number that was faster then others.
Inkfrog I think you have to add funds from Paypal.
There is tons of cheap prepaid smartphone plans that are great. Virgin mobile start at $35/month and boost mobile but I dont know there prices. I think it's around the same with them.
Laritha there is nothing free which can do this. You can create a stamps.com account (with a minimal fee) which you can print all the labels you need and then upload those #'s to paypal. you can also create a free usps account and print labels through there and also upload them to paypal