Heat registers, to flush or not to flush, that is the question.
When installing hardwood, one of the add ons is upgrading the heat registers to a flush hardwood mount. Don't confuse those for a regular mount you would buy at a hardware store that drops into the standard 4x10 whole for the forced air heating/cooling. Those things, in my opinion, is a waste of money, they are bulky, because they have to be, being made of real wood, they cant be too thin or they will crack.
These types of mounts defeat the purpose as to why install something different. If heat vent located somewhere under a piece of furniture, the unit would be crooked and unbalanced, if it was somewhere in the open, your soles and your toes would get acquainted with it, and not in the nice type of way.
My suggestion is if not going with flush mount to just buy the plastic ones, they come in all kinds of colours, including the natural red oak, they are less than 1/8" thick and are relatively cheap.
The flush mounts, as the name suggests are flush with hardwood, made of the same species of wood as the hardwood you are installing and would be stained the same color as the overall hardwood. They look great, or even better, you don't notice them, and that's something in the flooring business is a golden rule; If things are done properly, you never notice it, if something is done badly, every time you wake up and your vision glances over something that's not proper, it will be constant nagging reminder of a decision you have to live with.
This heat register is covered half by TV entertainment table/stand and in no way obscuring the airflow or tilting the stand.
So what does it cost to do heat mounts, relatively speaking, its a minor investment when it comes to overall cost of a hardwood flooring install. The prices vary from market to market, but I would say parts and labour it would cost between $50 to $100 per register. The mount themselves cost anywhere between $20-$50 each and the time it takes to do the precision cuts is the balance of the cost.
The last but not least inquiry that I get is if its possible to install flush mounts after the fact, be it that at the time of hardwood install, budget was tight or change of heart happened when some places received flush mounts while others did not (for cost saving measures). And the answer to that question is yes, its possible, labour cost would generally be slightly higher.
Here's an example of an existing hardwood receiving a flush mount.
Its a somewhat slow and tedious task of precision cuts but well worth the expense in the end. With staining and clear coat application on site to get best match. Same can be done with preexisting hardwood prior to resanding and refinishing, install new vents, sand and stain for best results.