Note for those interested in trying this as well:
Avocados do not breed true - you will not get a tree producing the same quality of fruit that you planted. It will be some completely random type of avocado ~~and it's extremely rare that these end up anything besides inedible.~~
If you're looking for a pretty tree: go for it.
Edit: based on further information it seems that you'll likely get an edible avocado but it will have any number of random mutations from the original. In the video shown below it was mostly seed with very little flesh, for example.
If you want good avocados buy a $20 seedling and guarantee that you're getting quality.