What do you mean?
Other slider (generally you need something bearing based and not cheap).
Or cheap fluid head for slider?

Two ideas just came to me a few weeks ago about what could be used for slider parts, they are:

1) Kitchen Cabinet Slider Rail Parts as basis.
2) Reverse Magnets as basis for some kind of slider. (much more complicated obviously).

I think both could create some really amazing sliders. I am actually having someone who
knows how to build stuff experiment with these ideas I gave to him and he is going to
get back to me and tell me what he will charge me to build something from either of
my ideas.

The cheapest slider/nopod idea I came up with on the spot one time was a paperback book on
a powered plastic 3 ring binder placed on a table in front of me. This is how I filmed
a seminar speaker once, if you have a light touch it works decent enough for panning and sliding
short distances while following a speaker walking around a podium.

For a really cheap (just slider) you could easily get a 1 metre metal straight edge/ruler, put talc
powder on it and have camera on another smooth light surface/book that you then slide along the straight edge by hand. This would be the cheapest useable slider I can think of right now.

Actually it seems easy to mod the Indi Slider Mini. Just ask my good friend.

Thanks for the links. Wow... I see why you kept insisting WF717 instead of WF717A.

How do you attach the 1st one on a tripod?