When it boils down to it, you're going to have to give one of three things to attend any conference: time, expertise or money.
Attending conferences are a great way to expand your knowledge by learning from industry experts and make key connections for your business. They're also expensive, with tickets often ranging between a couple of hundred dollars to several thousand dollars. This is all before hotel and accommodations.
So if you're running a small business, on a tight budget how do you get into these events without having to pay?
There are two ways: speak at the event or volunteer to help out.
If public speaking isn't your thing you can hop down to the second point. However, if you've got value to add to a conference with you being on stage, then pitch events on taking you on as a speaker. You can use a site like Lanyrd to find events which are close to you and fall within your niche--start here. It's important to note conferences often book their speakers six months to a year out, so don't waste time pitching events that are two weeks away from starting.
The event organizer is likely going to want to see a previous example of you talking to see if you're a good fit for the audience. If you have a video, send that over. If you don't have any video, then record yourself giving your presentation.
If you're going to go after speaking engagements as a way into conferences, start with small regional events and work your way up to bigger events.
This is the easiest way to get into a conference without having to pay. Contact the conference organizer months in advance and tell them you'd like to get involved, helping in whatever way you can. Helping work the door for a couple of hours in the morning can be well worth it if you're able to attend/meet people around the conference afterward.
Once again, if you're able to find a conference in in your local area, this is a bonus. When discussing your volunteering terms with the organizer make sure you are given enough free time within conference hours to attend the sessions you want. Also, if the conference is filming the speakers don't hesitate to ask for a copy of the keynotes for you to study after the conference.