It's changed a while since I went there, but my 2 cents.
In a budget around 200k, if it was my money, Milford Grange is probably most convenient. Some of the houses are probably a bit run down though if they've been let to students for years.
Curragh Birin would be another option, newer but slightly further to walk. Both would have a big concentration of students.
I'd avoid Elm Park - those houses were run down 20 years ago.
Outside that, you're looking at a slightly longer distance, so cycling would be involved. I'd look along the Golf Links road - you won't be tied to the student market when it comes to sell.
Have a look at the rent / share options in Daft to see what kind of rents they're getting.