>>I'm trying to find out how costly it was to sue WSL and if this is why so few 3rd class passengers pursued this.<<<
If you find out, let us know.
I'm not saying that to be a wiseguy at your expense. The problem in this instance is that not all of the records from that period have survived or come to light and I suspect that the information on the costs for individual attorneys have gone to the grave along with their firms. If their successors or heirs have any such records, they're not falling all over themselves to publish them.
Bearing in mind that the rest of this is pure speculation, (NOT verifiable fact!) I think you'll find that the reason a lot of third class passengers didn't persue this was because those who made it to the western side of the ocean alive were quite content to disappear into the woodwork and just get on with their lives. With the whole limitation of liability thing, it's not as if there was a huge pot to collect from.
One source you can go to regarding actual claims is
TIP | Limitation of Liability Hearings | Deposition of Captain Charles Johnston, Continued.
This is far from a complete list so if you or anybody happens to find anything filed anywhere which has yet to see daylight, the Titanic Inquiry Project would welcome any contributions. (See
TIP | Limitation of Liability Hearings )