If money is tight you have to prioritize your accessories. But you do have enough to get started. As one who wishes commuting was an option I would add in the following order. Add as money and time allow.

Lights, this is the only one that I consider a truly must have. The rest make it easier or more enjoyable
Bell or horn
Rear Rack
Some sort of bag, panniers, or baskets to carry stuff that may not fit in the seat or handlebar bag
Fenders
Smooth tread tires if you currently have knobbies
Now you get into clothing. For rain gear I have some cheap stuff I picked up at Mills Fleet Farm along with a reflective vest. Shorts and jerseys will be a matter of preference if you want them or not. Winter gear will turn out to be whatever works for you.