However, it has certain flaws: for starters, it assumes you know exactly what tax you pay, what mortgage interest rates (and fees) you qualify for, what your property taxes will be, etc, etc.
One of the key features about SmartAsset.com is that we do all that for you, and then let you tweak the numbers if/as you wish.
We also pull in live mortgage data (along with a number of other datasets) to compare various buy-v-rent scenarios that actually apply to you.
This is also only the beginning of the product. Apart from comparing buy/rent, we want to ensure users understand how much they can really afford (and why), how taxes will change over time, how their credit-score affects their ability to borrow money, etc.
Beyond that, there's also managing the process that goes with any major financial decision (what we like to call the "interest, learn, shop, buy" steps.