I think you're right to be cautious of pricing here, but more for the long-term implications. How will you justify the price rise to your customers when your video guy pads out his folio and ups his own price? Or would you take time out of your business to find and build a relationship with another up-and-coming freelancer?
OTOH, a 10% referral fee may be more worthwhile than it seems. The admin may be a hassle, but:
- does it take longer than the equivalent £X00 worth of design work?
- is the augmented product offering helping you attract and keep customers?
FWIW... for small jobs we tend to simply recommend a handful of providers for work outside the scope of what we do (precisely because of the hassle), but for more lucrative corporate-level work we tend to work on a finders fee basis. This way we don't have to act as middle-men and concentrate on the stuff we're good at.
Any other related co-ordination (project management, art direction, work review and so on) is charged at our consultancy rates.
Any work we outsource due to lack of capacity would be charged at our normal rates, and we'd take the hit on extra admin. The customer wouldn't be aware that we'd outsourced the work in this situation.