Pyramid is the only accredited PECS trainer in UK. If you do not have accreditation in PECS e.g. if you did not do their training for trainer course & seen it through to accreditation then you are on dodgy legal ground in selling yourself as PECS trainer
I know SALTs and SS teachers do routinely teach PECS to parents / other staff etc but under Pyramid rules its not actually permitted to hold yourself out as a PECS trainer. I don't know if Makaton have similar rules eg if you need to be accredited as a trainer to advertise yourself as such.
In terms of behaviour I agree I would want to know you had proper qualifications in behaviour analysis / ABA.
There is a market for it because parents are often told to try Makaton or PECS or social stories and then left to get on with it without proper advice, support and supervision.
The one thing I would have liked to do while sat on a waiting list for ASD assessment was a Hanen course. Thats a useful starting place for many parents.
You are assuming that Makaton, PECS etc is the right choice for each child - are you qualified to make that judgement? ABA has the best evidence base for autism so personally I would always direct a parent of a child with autism to ABA before paying for any of the approaches with less evidence behind them. I would want to know that my child needed PECS etc - we were given wrong advice twice on this - first we were told to sign / use Makaton although my son could not imitate and did not look at us, then we were told to use PECS even after my son had started to use single words verbally to request. The speech therapist never taught my son to imitate even though that is essential skill to speak. ABA told us to hold off on Makaton and PECS and got him requesting verbally within a week - basically as soon as they taught him to imitate / addressed lack of motivation he started to speak. As most SS teachers do not do ABA my concern would be you are ignoring the best approach which should be used first. I was pretty gutted that so much time had been wasted advising on Makaton / PECS - I would have been even more gutted if I had paid privately for the wrong advice.
If you don't have a existing client base then I would think you may be better linking yourself to something like Hanen / Pyramid or Makaton and having the certificates.
I have seen ex SS teachers advertise themselves as private tutors but that was more in setting academic programmes.
There are a lot of cheap ways to get / make symbols these days eg google images, sparklebox, mrsriley.com - or in our area the library have put communication software on their computers. Some parents even buy Boardmaker etc themselves. I think you would struggle to cover the cost of the time it would take you to make symbols.
I think you are right that there is a market but only because services are so poor, I do feel uncomfortable that parents should have to pay privately for a service which LAs have a statutory duty to provide. If the SEN bill ushers in direct payments for education then I suspect many more parents will ditch LA / NHS services for the private sector as the quality is so poor.
I also agree I would want to see outcomes. With ABA I have seen progress every single week far in excess of what my son achieved via LA / NHS provision. You would also need to be prepared for parents to use the fact they were paying you privately as evidence the LA was not meeting the child's needs - we got ABA funded via tribunal this way - few parents can afford to pay privately long term - often its a way of getting the evidence to improve the LA provision.