When I used to live in Japan, I remember hearing about this website a lot from my students and Japanese friends who got great deals on flights and accommodations both domestic and abroad. They have a Japanese website (obviously) which is filled to the rafters with accommodation choices all over Japan. I haven't really looked at the overseas choices, though. I referred to this website a lot when we were looking for affordable hotels in Japan. They have a very limited English website as well, which is where we found this Osaka hotel.
One VERY affordable hotel was near Shin-Osaka Station and I believe we paid a mere 6,500 yen for it. Unfortunately, I didn't think to take pictures but it was called something like Hotel Vienne Osaka or something like that. If you know what Japanese budget/business hotels can be like, well, it's exacly what you'd expect. If you don't, it's going to be a lot smaller than your average hotel room with a smaller bed and cramped bathroom.
Anyway, this hotel was very basic but had a clean bathroom, decent bed (a double, I don't think you can find a queen or a king unless you stay somewhere really flash), TV, tea making stuff and a bar fridge. There was a convenience store nearby (I think it was a Lawson's) for stuff like water, beer, snacks, etc.
Breakfast was even included!! It was a very decent breakfast and we saw the guy who checked us in the night before, clad in an apron bringing out rolls and making sure there was enough coffee. The most popular breakfast choice was onigiri, which are rice balls with fillings like salted fish, pickled plum, kelp relish or something. These are hand made (I think) on-site thus are limited in quantity and go quick. There were also baskets of rolls and what looked like croissants with jam, butter, etc. A soup dispenser held about 4 kinds of soup but they all looked like instant soup so I didn't try any of those. A big put of miso soup sat simmering away and that looked like they had made it on-site so I had a bowl of that. It was fine. Oh yeah, there was also a salad of shredded cabbage and carrots.
We chose to stay near Shin-Osaka station because we had to catch an early train the next day. If I'm ever in the same situation, I think I'd stay here again just for conveniece and value's sake. If you're just looking for a hotel in any part of Osaka, I'm sure there are good-value hotels all over town, so consult your guidebook for a neat area like Umeda, and cross-reference it with Rakuten Travel.