Do You Need a Domain Service
More than likely I'm going to be inclined to answer yes to this question. In the broadest sense, this question is ambiguous and refers to services that register new domains as well as those wonderful services that crawl through the heaps of expiring domains and sort the trash from the treasure. Regardless, in either instance the answer will still be yes, just for different reasons. In this case, however, we're only concerned with this latter question, and why, exactly, you so desperately need to use a domain service.
If you're looking into buying an expired domain, no matter the reason, a domain service is going to be your best friend for a few days to a few weeks. For starters you have to find the domain that you're interested in. This isn't as simple as just doing a quick Google search and finding the expiring domain that makes you happy; thousands of domains expire every day, and even if you have a pretty solid idea of what it is that you want, it would be soul crushing to try and sort through thousands of domains in a single day only to find that none of those domains particularly interests you. This is where a domain service specializing in expired domains comes in handy. While plenty of domain services have a convenient feature where you can search for expiring domains by keywords or name, only a handful let you search through these domains in mass looking for other points of interests. For example, if you knew going into the whole affair that you were more interested in buying an expired domain that had some popularity attached to it, well, good news- instead of having to dredge through a list of dying domains you can simply perform a search with the appropriate domain service, have the results sorted and given to you neatly, and then have the service continue to search automatically day to day and email you any relevant results.
While this may just seem like a really nice convenience, and admittedly the part about having your search results emailed to you daily without any further prompting is a bit luxurious, at this point the domain service is providing a necessary service. It isn't just difficult to sort through a long list of expiring domains and sort them by relevance- it's impossible. It would be difficult to find the time in a day to sort through a hundred expiring domains, but sorting a thousand on a daily basis goes beyond impractical and into the realm of imaginary. It's absolutely imperative that, at some point in the domain registration process, you will be using a domain service.