You should expect to spend about 10 percent of the money you raise on the costs of the offering, excluding marketing. I'd caution against spending money on marketing but remember it will take a lot of work.
Some legal and accounting costs will have to be paid before you can begin raising money. That would typically be at least $5,000 and could easily total 3 to 5 percent of the offering, depending on your circumstances.
The portal will also charge fees. They vary in structure and size but expect to pay 5 percent or more.
The items to consider - upfront platform fees $5-30,000 - platform percentage of raise 5-8% - some take warrants in addition - campaign support $5,000 - $35,000 - Legal and accounting fees - marketing, in Europe and US it can be up to 20% of the amount raised, in Canada and tighter markets, closer to 10%. This really depends if you need to build, buy or borrow a crowd.
Crowdfunding campaigns are not quick nor easy but the access to capital and the creation of a warm loyal crowd of advocates is invaluable.