The 300 MB/month limit is their free product. For $25/(Correction - not month, but year!) you get their pro package which includes: (from their upgrade option link):

  o Unlimited uploads (up to 50MB per photo)
  o Unlimited viewing of your entire photo library
  o Post photos in up to 60 groups
  o Download your original, high-resolution photos – whenever you need them
  o Upload and play unlimited HD videos
  o Browse Flickr completely ad-free
  o View stats on your account

I can't begin to explain how ridiculous the Flickr value proposition is for $25/year - and, indeed, there are some photographers with upwards of 100,000 pictures on the site.

[Edit - I was inspired to go try out Flickr just because of the hoofrah and this cool tool that let me move my instagram pictures - Wow - great Batch Editting, Set Collection, Image management. You can see the advantage of a tool with a decades worth of work into it. Signed up for a pro account]