Changing from Miracle Gro to Schultz 10-15-10 isn't really an upgrade. It's more a different brand of the same basic thing. If you do some searching locally, you should be able to find most of the following at cheap prices.
Fish Emulsion: 5-1-1. There are some small brands that get pretty cheap, especially by the gallon, because they're just trying to get rid of leftover fish parts. In a small grow, that roughly $15 gallon lasts forever and is a great source of Nitrogen. It's also a good source of Calcium, Magnesium and other micronutrients.
Bone Meal: NPK varies, N: 3-6, P: 9-15, K: 0-1. We recently found a new source at $1.50/lb in bulk. Some garden centers offer bulk fertilizers where you can get only what you need at a time at a good price, particularly for small amounts. Otherwise, get a big bag and just dip into it when you need. It's an excellent source of Phosphorus, Calcium, Iron, Sulfur, as well as a good source of Nitrogen, Magnesium, Zinc and other micros.
Palm Bunch Ash: 0-0-30 Best source of organic Potassium we know of. While usually not found locally, it's worth ordering. It's so good for flowering that if you give a full dose to a 24/0 vegging plant, it'll usually preflower without a dark period. The 10lb bag will last a small grow for years:
http://www.planetnatural.com/site/organic-potash.html
If you can get ahold of at least those three ferts, you'll have everything your plants may need in all stages of growth. You should also be able to call your grow fully organic.