Hi, I am an artificial installer but don't actually travel as far as Birmingham. I have had this comment that we charge quite a lot before - you should see how long it takes first!! I would suggest that so long as the surface does not require lifting the work should be done in house as there is no specialist equipment required. Most contractors would operate as a 2 man team for this and will charge for a full day - to cut back encroaching grass, clean the surface and reconsolidate, this is mostly because there are not many of us around and few clubs are local to us, the actual work will take as little as 3-4 hours depending how bad the surface is, but if the surface requires lifting then it will take a full day.
I don't think I am expensive at all, but I would not come out to do a job like this for under £400, but I am very thorough. To lift the surface, remove the shock pad, clean/add where necessary/ level/ reconsolidate the aggregate, restretch and refix the carpets and freshen the lines would cost £800 + Vat. This would be the same charge to replace the surfaces (carpet not included!!).
To do it yourself, brush the surface first then pressure wash it until clean, the moisture will then make it ideal to roll with a roller under 500kg, 2 -3 passes.
In season keep the surfaces clear of debris and roll occasionally to resettle the surface aggregate (team rota??), keep the surrounds clear of large weeds, encroaching trees and shrubs and coarse vigorous grass growth. Keeping the bottom of the net from blowing backwards and forwards will help prevent debris from getting on the surface. And suggest to the cricketers that wearing spikes and grounding the bat excessively will greatly reduce the life of the carpets. Cost £00.00!!
Hope this helps