I have a Harbor Freight 7 x 10 that I'm using a three roller steady rest on that I got off of eBay. Here is a link:
Steady Rest
I was going to make one myself, but quite simply I was too lazy and didn't want to run all over looking for parts. I mounted this on a block that I can clamp to my bench at various locations. What I really like, is I can not only use this as a steady to the left of my lathe when I'm doing tips and ferrules. I can also move this to the right of my lathe, remove my toolpost, and have a decent set up for shaft cleaning.
I was going to just mount a second chuck at the back spindle hole. However, that posed a problem because there isn't enough length between the front chuck and the rear. If you put a shaft in there with a little bit of wobble, it'll start whipping around like crazy and before you know it....bad things can happen
Not a bad setup...I got the HF 7x10 for $300 used on my local craigslist, then $50 on the steady rest and I'm good to go.
Regarding the tips at 14mm...you can get some of the boxed tips like LePro, Elkmaster, Triumph, etc..in sizes smaller than 14. However, most of your newer tips that I've seen only come in 14mm. Trust me, it's much easier to just slap a 14 on and trim it down to size as compared to using some gizmo to try to center a smaller tip. Usually you'll have to do some final trimming anyway.
Hope this helps...