trainboy325's right: add about 15% to those prices.
For instance: a Cheeseburger (comparable to a Hardee's or Carl Jr.'s Thickburger; going price $3.00+) went for $5.25 on #42/43. Soft drinks and coffee were $1.75 per 12 ounce (say about 330 ml) serving. Pretzels and chips were $1.75 for the "Big Grab" size bag you find for $0.99 in the C-store. Oh, yes, the souvenir playing cards were $4.00. The attendent attempted to hit me for $5.00 per deck. I pointed out his menu said $4.00, and he honored that price.
On my recent daytrip on #42/43, we took our own snacks, but still improved Amtrak's Food Service numbers by purchasing their Cheeseburgers in the Cafe/Lounge car for lunch. I had the presence of mind to bring a thermos of coffee. One of the smarter things we did was to bring several bottles of water plus the new drink packets made for a bottle of water. We therefore avoided the cost of soft drinks.
I also splurged on a 375 ml bottle of wine at $12.00 to share with my wife. She was having a great time riding an intercity passenger train for the first time, and insisted. Imagine my surprise when I picked up that day's copy of the Greensburg Tribune-Review, and saw an article by their wine critic stating the wine we had on #43 was a best buy at $16.00 for a 1.5 liter bottle!
Oh well. It was a very nice wine.