Which Eyepiece ....

I've got an ultima 9.25 f/10 with the standard Celestron 25mm Plossl EP that
came with it. I also have a TeleVue 13mm Plossl. In addition, I've got 10
and 20 Celestron Plossls. On top of those, I've got an f/6.3 focal reducer
and a Celestron 2x barlow sv series.

So, with the eyepieces I currently have, I can have several different
combinations of power. Yet I feel as though I should have a larger (wider
field of view) eyepiece. The question is, which one. Of course it all
comes down to price and I'd prefer not to have to spend more than 300-350 on
it.

What reccomendations might y'all have?

Thanks
Alex