Will MG Chemicals Positive Developer 418 Develop pre-sensitized circuit boards?
WHAT!!?? Those prices for NaOH are pure robbery!

Anyway, here's a trick how to compare chemicals: 
Every manufacturer has to provide material safety datasheet for each potentially dangerous chemical product. You basically go to Google and write product name MSDS and you get the document. It will contain the ingredients for the product. If you had some very basic chemistry training, you should be able to identify what's inside. 

So for MG Chemicals 418, we can see in the MSDS that main ingredient is sodium hydroxide (NaOH) and it's 7% to 11% by weight and that the rest is deionized water. 

I couldn't dig up the material safety datasheet for that exact developer (but you should be able to request it from manufacturer or distributor), but here's the concentrated version. If you look up ingredients, you'll see that it's "caustic soda" which is one of the names for NaOH. 

Based on this, we can see that the active ingredient in both products is the same, so they should basically work the same. Only possible difference could be the concentration, since I couldn't dig up the MSDS for the exact product you've been using. 

Also here in Serbia, 1 kg of NaOH costs between $1 and $2 and you can make around 100 l of developer with it, because usual concentration is 10 g of NaOH per liter.