Do not - I repeat - Do NOT use a coffee grinder, even if it is a burr grinder. Your crush will be too fine and you will end up with barley jelly and unable to sparge properly.
You can use a rolling pin or heavy vegetable can for small grain bills. Your extraction might be a little low so you might want to bump up your grain bill by 10% and have some DME on hand to “Fortify” your first few batches. Calculate your efficiency on each batch you make so you will eventually know if you need to add 10%, 5%, 15% etc…
Keep your eyes out for a used grain mill, I started with a Corona mill and it was only about $35 new so you might be able to find one cheaper on craigslist or some of the used brew boards.
Also, since you are in NYC there are quite a few brew clubs in and around the city, you might be able to find a brew buddy with a mill if you join one of the clubs!