Of course, do buy specials and custom, but only where really necessary, because they cost more, they take up a lot more time for everybody concerned, and there is far greater scope for problems and error. It takes on average two years to bring a light to market. Besides all the aesthetic considerations, it takes time to sort out the materials, moulds, jigs, electrics, electronics, the subcontractors and the quantities to be ordered from them, the packaging, the documentation, and to meet all relevant legislation, at a price that the market will stand.
But once all this is done, standard items are produced as planned, in appropriate quantities. The team that created them move on to the next design.
A special or custom item changes all this. The team has to be taken off what it was doing. All the implications of the changes need to be assessed and appropriate steps taken -- ordering special materials, perhaps, in inefficient quantities, making new jigs, etc. etc. Production of the nonstandard items interrupts the production of standard items, so there is an opportunity cost.
All this also means that a custom item may be late: it will certainly take longer to deliver.
From the specifier's perspective, a bigger problem can be that they take time to cost. (It is not unusual for us to be rung up on a Wednesday in the expectation that a new light can be designed and costed by the end of the week. This is not possible.)
The cost of a standard item is already printed in the price list, along with its full specification. But, for a special or bespoke item, all the designing has to take place before it can be costed. It is surprisingly difficult to give accurate estimates: a small change can result in substantial upcharges -- or none at all.
A recent incident showed a poor grasp of basic geometry on the part of a specifier. She doubled the radius of a design that was in the shape of a sphere. She assumed (in fact, insisted) that this would mean that the cost would be double. But, besides all the other possible financial implications referred to above (plus the light being a lot heavier), the outside area of the sphere, and therefore the labour and materials used, was increased by about four, not by two (the surface of a sphere is given by 2πr2, therefore a radius of 2 gives a surface area of 50.27, whereas a radius of 4 gives a surface area of 201).
So for the maximum value, the minimum waste of time, to minimize problems and to minimize delays, buy standard items!
In fact, a good designer should pride herself on not specifying specials except where absolutely necessary -- it is a measure of her professionalism. And the studio should come down hard on those that do specify specials unnecessarily. The studio's asset is designers' time, and it is being wasted unnecessarily. (And remember that the purchaser will probably buy something else anyway.)
By the way, note that specials may not be allowed, even when they are technically possible. If the maker owns the design outright, there is usually no problem. But if the design is owned by the artist, architect or studio that created it:
1. they may not give permission for the design to be changed. In fact, we've known them to take grave offence when someone has tried to muck about with what they spent so long perfecting
2. the maker will be paying the owner a royalty. The nature of the royalty agreement may make non-standard versions impossible.
Note: this series of posts builds up into a single Briefing, a PDF of which is downloadable here: A Briefing on Value for Money when Purchasing for Hotels.