Boot gloves are just good insulators. They work well but... They are effective only if they are put on before you head out. Depending on the outside temp, they can start losing their effectiveness as soon as you're outside. They can get wet and they can be obstructions to your buckets for those who like to unfasten and/or adjust them on the fly.
As for toe warmers, these chemical packs work really well but they have a shelf life of about 1 year. Buying them online is not a good idea and either is buying them from TJ Maxx and such (Maxx/Marshalls are surplus stores for these items). At half price, warmers aren't good bargains when they aren't hot or last less than half as long.
Like most quality goods, local ski shops and outdoor stores are your best bet. But, the best bang for the buck that I've found for warmer packs is at Walmart, especially in the Northeast. They stock up in huge quality in late fall every year for the hunting season. There are several styles available (feet, toes, body, fingers, etc.) and they are cheap (like 2/$1 for toes and 3-4/$1 for fingers). This allows you not have to buy in fixed amounts and they are always fresh stock. When you run out, you just run out to get more. We swear by doing that for several years now.