I’ve had some success packaging domains together in a bundle for sale to end users. In my experience, this has worked out better as a secondary sale to end users who have previously purchased single domains. This made contacting them with the offer that much easier. I typically start out these types of emails with the following.
“As someone who has purchased a domain name for this industry in the past, I’d like to give you the first opportunity to purchase the following names. The price for the package is $x,xxx and the domains will not be sold individually.”
The immediate reaction will be to take the bulk price and divide by the number of domains to get a unit price. This has it’s advantages and disadvantages. The domains in the group will be of varying quality, so it makes the good names look like they are being offered at a great price but can make the buyer question the lesser quality names. I’m not at all suggesting that you throw in junk names. If you do, the buyer will probably counter with an offer to buy just the better names and at the unit price they calculated or below (I’ve burned myself doing this). You’ll end up doing your client and yourself a disservice.
If the lesser quality names are decent, they will hold their own as part of the package and the buyer’s desire to obtain the better quality names will result in a sale (this has also happened to me). This method makes it easier to sell multiple related domains in one sale as opposed to multiple individual sales. Efficiency lets you sell at a better price.