I don't think we can post links here. But my suggestion, if you're going for super affordable, are greeting cards for dog lovers.
There are dog lover cards I saw online that you can also display (from Blue Melon Cards). They send it directly to the recipient with your personal message at the back. Just google "dog lover cards you can display."
It's hard to post links for specific things without knowing more about what the recipient likes.
For me, I love Etsy for gift type things. They're so original and typically well made. I've received custom paintings of my horse (and I'm hoping to get one of my dog this year). Personally, I would steer away from coffee cups and generic things like that.
I absolutely adored For the Love of a Dog by Patricia MacConnell, it's a fantastic book that gives greater insight into the way dogs think and has some wonderful stories in it. Every person I've lent it to has enjoyed it.
If you are inclined to be crafty, I've got some ideas for things you can make. If not, I'm sure you can find them on Etsy!
Last year, my boyfriend, his parents, and my brother all got a dog within a week of each other, so I was definitely looking for some good gift ideas! After they got their pups, I made them all little personalized treat canisters and filled them with goodies, which they all LOVED. The canister wouldn't even need to be personalized. You could find a cute one and fill it with treats and stuff.
For Christmas, I made everyone leash hooks. This is definitely something you can buy online and there are really cute ones on Etsy!
Dog artwork is also a great choice. I made a string art piece for my dog, and I'm considering giving them as gifts to everyone this Christmas!
2. Leash hooks for Christmas
3. Leash hook I made for my dog and that I sell on my Etsy store (not sure if I'm allowed to post the link, so I'll refrain).
4. String art (also on my Etsy shop)