What do you mean it can't run the resolution for your Mac?
The TV will accept certain resolutions based on the connection you are using on the TV. To change the resolution being sent to the TV, you would go into System Preferences - Displays while the TV is connected.
New or different cables &/or using a different connection on the TV would be much less expensive than a new monitor for which you would have to do the same thing - adjust the resolution being sent to the monitor based on the resolutions that monitor will accept.
You may want to have a read through the first 2 posts
here and then post back with the info required if you would like to attempt getting your current TV working - along with what you have tried, adapter and cables you're currently using, what are the results...
(Some Samsung's are just plain not going to work - I admit. But, I am unwilling to make that assessment based on what you've stated thus far. If you've been getting a picture at all, then you should be able to get that TV to work.)