Is there a spell that would allow a character to Astro project themselves to another part of the same plane they are currently on? i looked at the spell astro projection, but i dont think it quite works that way. 

Im basically looking to have an illusion version of someone appear and be able to speak with and see the players ... with or without any physical interaction. 

Think what luke did in the last jedi .... 

any ideas?

Not one I can see, although Sending or Dream could get the message through. Remember though, as the DM you are under no obligation for your NPCs and monsters to use only abilities available to the party. If you need a creature to send an illusory version of itself across the material plane, then you can just give that ability to the creature. Limit it to once per day if you want. Or invent a magic object that they possess which gives them that power (but then be ready for the party to try and acquire the magic object for themselves).

I want to second what Regent told you.  The stuff in the Player's Handbook restricts Players, not the Dungeon Master.  If you want your guy to cast this type of spell do it.  Don't feel a need to explain to any player that might ask *how* it was done.   Heck, this weekend in my home game, I had the BBEGirl do this exact thing INSIDE the party's Leomund's Tiny Hut.  She scared the bejeezus out of them and not one of them (one is quite a rules lawyer) caught me on that whole "stopping all spell effects" thing either.  It was cool, it was required for the story, and the players were engaged with it.  So to heck with the rulebook.

I've used Mislead to do something similar in the same city with a short travel time. Let the illusion travel through a gate or teleport in some way and you could accomplish the same.

Project Image

7th level, range 500 miles, lasts a day. You project an image of yourself which you control and can see and hear through it. The image is basically a ghost - no physical interaction.