In need of a good tachometer any help is greatly appreciated ...... Thanks

To begin with, few engines hold a perfectly steady RPM. There is always some variation, small but there. Digital tachs respond to this variation, and some probably add a bit of their. In all cases that I have seen, the displayed RPM fluctuates, more in some cases than others, but it is almost always there. It is often hard to com eup with even an average reading.
On the other hand, the analog tach, those with a mechanical needle, do not respond to the engine's variations, and being relatively slower to show a reading, actually average out the variations and display a valid value.
I am referring to "engines" - glow and gas. I have no experience with electric "motors" but with many I see advertised, I would imagine some differences in quality is to be found. The same applies to speed controls. If there is a variation in the props RPM, the digital tach will increase the error displayed. The analog tach should provide a more useful average information.

Plenty around. You want one with a button switching between 2 blade and 3 blade props.

20 $ max.

Over the years I have had and borrowed quite a few., all have worked just fine.

Are you asking someone to give you one or sell you one at a greatly reduced price or are you asking where to find one for sale at retail?

I'm looking for recommendations for one ..........

This is the best one on the market - http://www.fromeco.org/products/05frctnc/default.aspx

Thanks to all, Just ordered the fromeco tnc ....Happy Holidays