No, it is certainly possible to file registrations yourself. An attorney would just supervise a paralegal who does the actual work, so it might not be all that expensive... but there are some important ways to "mess it up" and have to start over (such as naming the wrong owner, or describing the wrong goods or services).
As you probably know, registration of a trademark in the USA is COMPLETELY optional, and you have rights that can be enforced in state and federal courts. The vast majority of trademarks in the USA are not registered anywhere.
If you MUST register, consider registering in your state, for starters. It is inexpensive, quick, and will give you some feedback on things you could do better if you file in the USPTO. If you searched the USPTO properly, and search your own state's registrations, you will get a good idea for how safe your choice is for REGISTERED marks. If you have seriously googled and sorted through the links, you'd know if anyone is using a similar brand in a similar field already.
The professionals who do "clearance searching" have access to hundreds of databases and can whip out a comprehensive search in a couple of days. I used to use CorSearch for pre-screening and searching.
Edit: Please ignore stupid answerers that don't know the difference between copyright and trademark and anyone who thinks you have to register a copyright before you own it (which is totally false).