ihave motherboard z87- hd3 can i get 4790k and overclock on this motherboard ????

For future reference you can go to the motherboard page, CPU Support, then find the list of supported CPU's which includes the BIOS version needed:

*Also, what does an i7-4790K cost?
Last I checked they were hard to find and cost between $400 and $500 new, and at least $200USD used.

You can get an R5-2600, motherboard and 16GB DDR4 (i.e. 2x8GB 3200MHz DDR4) for roughly $350USD.

Windows 10 license is now tied to your digital account (i.e. MSN) and there's a good chance now that simply moving your Windows drive to the new motherboard will work perfectly.

Not trying to push AMD but that does seem like a better option for the price. Sure performance in some games will be better on the i7-4790K but you get 50% more cores/threads with the R5-2600 which can help game smoothness and FPS in other games (especially as games need more CPU in the future) plus AM4 isn't dead yet and the Zen2/3000 series should be compatible.

*In fact, I'd consider doing what I said above but get an R5-3600 CPU instead later this year (which may be roughly 20% faster than the R5-2600).