It's possible to do it for under $5000, if the bride doesn't expect all kinds of expensive stuff.
For my wedding, we planned it in 3 weeks. Yes, I said weeks. My hubby had just gotten home from a deployment in Arizona and had just gotten orders to go to Iraq for 18 months. Of course, we didn't have 100-150 people, but we did everything to cut costs and made our budget in to about $1200ish. The pastor of the church we chose waived her fees and all we had to pay for was the lady that helped clean the church afterwords. We played our own music instead of having a piano player. Our reception was at the church. We made our own food the night before and warmed it up in several crock pots the day of and it was amazing. We did our own decorations that were purchased at craft stores like Micheal's or AC Moore. I bought my dress on Ebay for $250. Thankfully, hubby already had his dress greens to wear (I love a man in uniform lol
). For flowers we found a local vocational school with a horticultural program and paid basically for the cost of the flowers. I bought my tiara at AC Moore and a simple veil there too. Instead of going to an expensive cake shop, we just went to a local bakery and got an "altar cake".
Just to give you some ideas of different ways to cut costs. Maybe check with your favorite restaurant and see if they cater? We were going to have food catered from my favorite BBQ place but decided to make Rigatoni instead. Hahaha re-reading my post makes my wedding sound awful, but it really was nice.