I have heard it said on this forum many times that unless a coin is worth 150.00, the you won't come out ahead due to grading costs.
If you like losing money, ignore the rest of this 
Consider the grading companies (TPGs) are businesses:
1. Ask yourself why a business exists.
2. TPGs record/publish how many of the highest graded slabs, let's call them "money-slabs," they have assigned.
3. The less money-slabs assigned a specific coin increases the market price people pay to own one.
4. Therefore more and more people pay the companies to slab their coins hoping for a money-slab.
BTW:
5. The invention of online registry set competitions has boosted the prices of slabs considerably - another genius marketing idea.
B/c
TPG's use no verifiable scientific standards for grading, cracking out a coin and resubmitting (even to the same company) means different grades can/do result. Hence the company's profitable "re-slabbing game" exists with people re-submitting and hoping for a money-grade slab.
If you just like collecting slabs for what they are, then go for it and enjoy the slabs/hobby (including registry sets)!