Hey, welcome to DIS. You're from my neck of the woods.
Yes, Disney is expensive but the one thing I can say about them is that they are usually worth the extra premium you pay. I wonder if you can renew your vows on
Castaway Cay for that $1900? That would be SOOOOO worth it to me!

I guess it's going to depend on how elaborate you wanted this. Is it just the 2 of you or will you have family cruising with you to witness it?
Now, Disney does things Disney style, but I think I'm getting alot of bang for the buck on Princess and yes, we're doing a vow renewal while onboard.
Basic - $205, the couple receives the ceremony, an orchid bouquet and boutonniere, a commemorative certificate, a bottle of Champagne, two Princess-engraved Champagne flutes, and a framed portrait of the ceremony.
Premium - For $485, the couple receives the ceremony plus Champagne breakfast in bed, two robes, a 30-minute massage or facial per person, choice of canapes in the stateroom every evening, and a personalized invitation from the Captain to visit the bridge while in port.
I booked the basic for a few reasons. First, we're in a suite. I can get a champagne breakfast in bed if I wanted it, I already have robes in my room and I don't need any to take home and we already have our spa appointments booked for the week and I need longer than a 30 minute treatment. DH had no interest in doing the bridge tour and they're only offered while in port. Well, we'll be visiting in the port and don't want to cut our time short just to attend a bridge tour.
So DH is in for a surprise when we embark on our journey. I've kept the vow renewal a secret and it's KILLING me. DH's mom knows and she'll be cruising with us so I have her to bounce things off of.