I should say go for the DDJ-RZ!! I have it and LOVE it. It has some problems to BUT if you look into the support-forum here on Pioneer DJ you will find TONS of problem-tickets regarding the DDJ-1000. I would not go for the DDJ-1000 before the fixed all the "baby-diseases" regarding the DDJ-1000.
But it it off course also a matter of investment, RZ is more expensive, maybe can find it used as you wrote.
Also RZ has more tech-features than the 1000.
But the 1000 has some new features that the RZ dont. You get so much more for your cent in the RZ. It is not worth ALL problems it has just to get the color-screen.
I only use my RZ at home so I have a 22"-monitor connected to it.
But if you wanna use it LIVE then maybe the color-display WILL give you value to buy the DDJ-1000.
I suggest you Open BOTH RZ-tech and 1000-tech product information pages on Pioneers homepage and then compare them.
After that ONLY you can descide what is important to you and what works for you setup, needs, requerments and your type of use. I think you willl be most satisfied with the RZ. It has sooooooo MUCH tech-features and abilities in it. So many functions to use with Recordbox software. AND it has been used for some time now and all the baby-diseases are mostly solved. It is a stable piece!! I love it as I said. Use RZ together with the XP1 and the opportunities are unlimited!! =)
If you still dont can deside I would recommend you to open some review-videos on Youtube for bothe DDJ-1000 and the DDJ-RZ. There you will see them in closeup and see them actually used. It will give you valuble information in your decition. But be carefull just not to "fall for" a so bright and colorfull or beutiful presentation in an Demo-video. Better is to look at review-videos from a thrid part.
This is one of the videos that convinced me of the DDJ-RZ:
https://www.youtube.com/watch?v=PWrTBNk77fI
DDJ-1000 can you see here:
https://www.youtube.com/watch?v=nPOGQLMgeZI
Hope is was some useful help. Good Luck!