Hi crazy mom- There are some affordable, high quality foods out there. I have an almost 8 year old Great Dane and I understand how pricey it can be to feed them.
Annamaet Ultra from HDM’s list is $70 for a 40 pound bag which comes out to $1.75/pound. It has 480 calories/cup so you’ll feed less of it than you would other foods which will also make it stretch further- a good bang for your buck. http://www.chewy.com/dog/annamaet-ultra-32-dry-dog-food/dp/41926
Annamaet Extra is also a possibility. It is lower protein at 26% instead of 32% (I prefer higher protein for my dog). It is $53 for a 40 pound bag ($1.33/pound). It is not as calorically dense as the Ultra at 425 cal/cup so you would need to feed a little more of it. http://www.chewy.com/dog/annamaet-extra-26-dry-dog-food/dp/41927
Dr. Tim’s Kinesis is good too. It’s $61 for a 44 pound bag ($1.39/pound). It has 415 cal/cup and 26% protein. http://www.chewy.com/dog/dr-tims-kinesis-all-life-stages-dry/dp/37810
Victor Select Chicken Meal and Brown Rice or Lamb Meal and Brown Rice are also affordable. The chicken is 391 cal/cup, 24% protein, and $55 for 40 pounds ($1.38/pound). http://www.amazon.com/Victor-Dog-Food-Chicken-40-Pound/dp/B00COVMFW4/ref=sr_1_6?ie=UTF8&qid=1389619583&sr=8-6&keywords=victor+select+dog+food
The lamb is 381 cal/cup, 24% protein, and $59 for 40 pounds ($1.48/pound). This would be good so you can alternate proteins and not feed just chicken all the time. http://www.amazon.com/Victor-Dog-Food-Chicken-40-Pound/dp/B00COVSBL8/ref=sr_1_9?ie=UTF8&qid=1389619583&sr=8-9&keywords=victor+select+dog+food
Those are all grain-inclusive foods. Grain-free cost a bit more and I don’t know exactly what your budget is. I think Earthborn Holistic is the most affordable and high quality grain free food out there. Meadow Feast and Coast Catch are on HDM’s list. They are both $47.99 for a 26 pound bag ($1.85/pound). The MF is lamb-based, 26% protein, and 400 cal/cup. http://www.chewy.com/dog/earthborn-holistic-meadow-feast/dp/36414
The CC is fish-based, 32% protein, and 435 cal/cup. http://www.chewy.com/dog/earthborn-holistic-coastal-catch/dp/36406
As far as your Danes putting weight on, as long as their not ribby it’s ok for them to be on the lean side. It’s better to be lean than overweight. You don’t want added stress on the joints.
I hope I helped with the food recommendations. If you can afford it, I would try alternating the grain-inclusive foods with grain-free foods. You could do Annamaet Ultra, Earthborn Meadow Feast, Dr. Tim’s, Earthborn Coastal Catch. That way you rotate protein sources (chicken, lamb, and fish) as well as protein percentages (32% and 26%).
