Fair question! I guess up to £40 would be ok if it offered fully buffered signalling, a charge pump and one relay I could use for the spindle. I'm not fussed about opto isolation as the drivers include that already, and won't need any more relays initially. I'm just looking for a solid solution to get me started, because when I have looked at motion control options, the choices are overwhelming - and I've not yet even decided what software to use, hence really don't wish to invest in too much before I have a play.

Does that seem reasonable? Maybe I'm being over cautious, but the more you read about the cheaper BoB's, the more you think they are all unreliable - and that is what I'm hoping to avoid at this early stage.