Do you know anyone of who would be able to recite Tehillim for me in exchange for tzedakah?
It's best to speak to your local rabbi, who I'm sure has no problem finding someone needy and happy to say Tehilim for your sake. Tzedaka of those who live in one's city takes priority! But in addition, this in no way should be in your place. Hashem doesn't like "intermediaries" on our place. He's our Father and likes to hear from each and every one of us! Not to mention that your own Tehilim and prayer is surely said with special concentration. Even if you have trouble saying the texts, simply talk to Him in your own words. You will find this especially beneficial.