Wanting an Engagement Ring

Jules • Young married soldier just trying her best to keep everything together.
So, first off I'm getting married. We plan on June 14th so far but it may fluctuate by a day or two. We are just doing a courthouse wedding to keep it simple and cheap. I never wanted a big wedding and he doesn't care, we just want to be married. 
Here are some minor details to help explain the situation;
We are both entering Army Basic Training in August of this year. 
Money is tight for both of us. His mum just borrowed $6,000 for bills and such. (she's a single mom with 7 kids, his dad passed away some years ago) When his mum is in a tight spot he never says no. If she needs money he will help her. She's an immigrant and her whole family lives back in the Philippines so she doesn't have much support other than him. He's an amazing and selfless young man.
We are both young. 18 actually. We've been dating for a while and decided we wanted to be married before we ship out for basic training. 
I'm probably going to lose my job this week. I had a friend pass away on Monday and found out the next day. I was very distraught and called off. He was a very close friend of mine. My boss informed me that if I missed another day of work I would be terminated. The same friend's funeral is on Friday and I really need the closure so I'll probably be quitting or getting fired.
We need to use our current savings towards cost of living over the summer and whatnot.
Here's the thing; I still want an engagement ring. I do. I don't know how to tell him though. I don't want anything expensive, I don't want diamonds even or anything flashy. I just want something on my finger that says I'm his. I offered to pay for wedding bands for once we actually are married and he offered to split the cost. But until then I'd like a ring. 
How do I tell him that?