If you are working with a limited budget, you have a couple of options.
First, you can decide how you are going to prepare and file your application - yourself (if the jurisdiction of your choice permits you to do so), with the help of an all-around lawyer, with the help of a specialized trademark attorney, or using an online legal service such as Trama. Each of these has a different price-to-result ratio. You can find the complete comparison of these options in this article.
As a second point, since the cost of trademark registration depends on the number of countries you choose, you can always start the registration in one country first and expand your registration to more countries later. It is always a good idea to first register in a country where you have the biggest customer base, as the chances that your brand might get copied are relatively high.
Third, you can also limit the number of classes of goods and services listed on the application if necessary. Usually, IP offices charge a base price for the application, which includes one class, and then an extra fee for each additional class. If the budget allows, we'd advise covering all goods/services you offer, which usually means choosing multiple classes. However, if you only have the funds for one class of goods/services, make sure to choose the class that reflects the core of your business.