MakerGeeks. They have plenty of sales (BF sale I think is 25%), bulk pricing and and by far the best PETG I have ever used. I've only gotten their maker series, but its fantastic. I don't think you need to splurge and get the more expensive rolls unless it comes in a color you just have to have. The stuff bridges as good or better than PLA so you save a lot on not having to use as much support material. The default settings in Prusa Control are perfect for it as well. Shipping is free, but will take > 1 week.
Sometimes I'll get PLA from Amazon. AMZ3D I think is the name of the company, not a lot of color selection though. Prime shipping, was like $17 and had the best black PLA so far. Stay away from MeltInk3D. Their PLA is garbage and had a lot of snags that ruined prints on my mk2. Hatchbox is popular. I didn't like their PETG. eSUN PETG is the worst. My last print broke just trying to take it off the printer... re-printed in PLA and had no issues.
PushPlastic has some nice PLA. Most of my rolls have been great.