Costs/Fees Associated with Applying for PR under Express Entry (based on my experience with and understanding of the process)
EE Profile Expenses
Expect to spend anywhere from CAD$500 - $2,000 getting your ECA and language test results, depending on which assessment organization you select, how many credentials you need assessed, which language test you choose to take, and in which country, and how often you have to take the test (or have results re-evaluated) to get decent results. If you have a spouse, and plan to have his/her educational degrees assessed and have him/her take a language test to increase your CRS Score, you'll need to consider the costs for him/her as well. The rest of the Express Entry profile has no associated cost.
Application Completion Expenses
If you get an ITA, and choose to submit an eAPR, there will also be costs associated with collecting the documents you need for the eAPR, including but not limited to medical exam fees, the fees to obtain police clearance certificates, and any fees to obtain letters from your financial institutions to show proof of funds. These costs vary by person, depending on their particular application (and the resulting required documents) and where they live. (I personally paid approximately CAD$300 to get all of my documents together).
Application Processing Cost Recovery Fee and the 'Right to Permanent Residence' Fee (RPRF)
If you submit an eAPR, you will have to pay at least CAD$1040 (more if you have dependents accompanying you). This represents the application processing cost recovery fee and the 'Right to Permanent Residence' Fee (RPRF). The application processing cost recovery fee must be paid at the time of submitting your application, but the RPRF can be paid at a later point during your application’s processing; IRCC will contact you if and when you need to pay this.
FSW Applicants’ Required Settlement Funds
If you're applying under the Federal Skilled Workers (FSW) programme (unless you have VALID arranged employment in Canada WITH a valid labour market impact assessment (LMIA) if your job isn't LMIA-exempt), you will also need to prove that you have at least CAD$12,300 in available, unencumbered funds to settle adequately in Canada (and this amount can't be obtained through procuring a loan). If you have dependents, you have to show more, depending on how many dependents you have, even if they're not accompanying you to Canada. (CEC applicants do not need to provide proof of settlement funds).
All in all, the entire process will cost between approximately CAD$1,800 - CAD$3,500 (for a single applicant with no dependents), and most FSW applicants will need to be able to show at least an additional CAD$12,300 in available, unencumbered funds to satisfy the settlement funds requirement (for a single applicant with no dependents).