As a proud member of the senior services I cannot fathom not having a printer. Old school until the end.
Anyway, you can plain paper print at a Fedex store for about 70 cents or so, I believe, but by the time you travel there and do it, or sent it in online and then retrieve it, all your postage savings are gone.
So I figure it's get a cheap printer (plus you'll want a cheap postal meter - Walmart, Amazon) or keep using the USPS services.
I may be overlooking some magical way to get a label made from an online postage discounter and, if so, please advise me as well as Shawn.
As for my method of saving money on postage, I use Pirate Ship for discounted packages - typically bubble mailers - but have used for Xmas boxes as well. I have a Dymo postal meter that remains from my business days to check on weight which is a necessary component of cost (along with mailer/box dimensions).
But I also use the meter to check on weight on my rigid mailers (nonmachineable stamp is for 1 oz or less, up to 2 oz required 2 regular stamps, have not encounted any pwe type trades that weighed more than 2 oz). Pirate Ship will store info on people you mail to so it saves a good deal of time if you have repeat mailings - like I do with you - and then I print right to my Epson eco smart printer. Cut the printout down to appropriate size as required, use my packing tape to afix it and I'm done. Probably takes less that 10 minutes or less total time for the entire process. Even though USPS keeps raising prices I figure I have saved about $2.50 or more each bubble mailer and more on the boxes I have sent.