Christian book stores usually have a section for "devotional" books. Some of them are good. A lot of them, in my opinion, are fluff.
An alternate idea that I'd like to recommend is reading a commentary or a systematic theology by reading a couple paragraphs or a section per day.
Some recommendations I have would be Warren Wiersbe's commentary on the Bible or a systematic theology by someone like Wayne Grudem, Millard Erickson or Norman Geisler.
Some might be strapped for money. Each of these books I recommended above, if read a couple paragraphs, or a section, at a time, would take years to get through. So if thought of that way, $30 - $60 could spread over many years. It can come down an average of a few dollars per year with one purchase.
Another idea that would be an alternate is to do an audio devotional. For example, J. Vernon McGee's Thru the Bible daily radio program (or podcast now in these days) could be used in place of reading a commentary like Warren Wiersbe's if you don't do well reading. McGee's radio program/podcast is 26 minutes a day and gets you through the Bible in 5 years (plus, you can get this for free). What do you do after you complete it? Do it again! Why? I can't remember everything I heard in the last 5 years.
Actually, one can listen to Wayne Grudem teach through systematic theology for free on itunes also these days. So you can do Bible commentary and systematic theology audibly for free these days. I learn best by a combination of methods. I like audio. I like reading. I do better with both.
I recommend eventually getting through both a book commentary (like Wiersbe) or audio commentary (like McGee) and systematic theology. Doing both of these will really ground you in God's Word. You won't be tossed to-and-fro by every wave of teaching that comes down the pike.
I have found all of these make great devotionals and they ground a Christian in a much deeper knowledge of Scripture than any devotional you can buy off the shelf. I have been blessed for years by doing this. And since I like being blessed, I assume you do too, I thought I'd share something that has benefited me over the years.