I guess it depends on what you expect for your $25. Are you looking to compare it to the dining plan? If so you want to find places where $25 will get you a beverage, entree and dessert for $25 (tax included, but tip excluded).
Or are you looking for places that have entrees with a menu price under $25? This would open up an entire range of choices that the first option would eliminate.
I'm going to assume that you mean the former and not the latter.
- In Epcot, I like the vegetarian menu at La Hacienda de San Angel. The cheese empanadas are $14. Iced tea $2.50 and helado is $6.25. With tax, the meal comes to $24.23.
- In the HS, the 50's Prime Time Cafe has Dad's meatloaf for $15. Iced tea is $2 and you can get an ice cream sundae for $5. Total with tax is $23.43. Or hit up the Sci Fi for an Angus burger ($15), Coca-Cola ($2.60) and fruit salad ($6) for a total of $25.13.
- In the MK, a well-kept secret is the Plaza restaurant. Their vegetarian sandwich with slaw and fries is awesome and only $11. The most expensive entree is $17. Soft drinks are $3 with free refills. For dessert, a sundae can be had for $5 and they are very generous in size. Total price $20.24 for the veggie sandwich, drink and dessert.
- In the AK, you can sometimes get out of the Rainforest Cafe for under $25 if you stick to burgers or sandwiches.
TBH, it can be difficult to stay under $25 for an adult meal if you include desserts. Drop the dessert and there are a lot more choices. But if you're trying to compare apples to apples with the dining plan, it gets more limiting.