Hoestly, A good Filter and a HOB skimmer would be great for a tank that size.
I would agree with your LFS. A sump for soemthing that small would be troublesome.... perhaps.
Location, Plumbing, Power and so on.
That said, It also depends on what you wana accomplish. What livestock your going to have. A sump would give you some greally nice filtering options. But I really think a 'Fuge would be otherkill.