This depends on the type of hearing loss you have.
For simple age related high frequency loss, cheaper, over the counter aids can offer great improvement. Be wary of the ultra cheap type though. They are often just amplifiers and don't target specific frequencies.
Some mid priced hearing aid companies, such as Eargo, offer online or over the phone consultation & testing. Some also have free return policies if their products don't help.
Before spending money on any product, it's always best to be evaluated by a professional. Some types of hearing loss, such as that caused by impacted ear wax, can be remedied without the need for hearing aids.