2003 Toyota Rav4 4x4 2.0 4cyl, having startup issues...

Hi, First time posting here, hopefully the last (not that I don't love you guys or anything), but my Toyota which has served me well for 65,000 miles with very few issues outside of basic upkeep. Recently though, the cars been struggling a bit to start up, especially after not being started for several days. If it goes about 24-48 hours between being started, the engine lurches one or twice when I turn the ignition key, then starts up like it should after a couple seconds. once I start driving it around, and stop the car, then go to start it again, it fires up nice and quickly. The real problem hit me when I went on vacation for 8 days this past week and weekend. I came home today and went to start my car, so I pressed the clutch (It's a manual), and turned the key, and the starter motor whined and spun for almost ten seconds, before the engine slowly burbled to life. Once it started, it drove fine, felt great, and after driving for 15 minutes, I stopped for about an hour, went to start it up again, and it went fine. Anyone know what the issue is here? My dad suggested it needs new spark plugs, my brother's convinced the starter motor is shot, but it sounds like it works just fine.

The battery was replaced most recently at 50,000 miles along with an ignition and full motor diagnostic, which was fine. I'll be glad to provide any further information. Is this something that would be expensive to fix, if not could I possibly do it on my own?

Also, no lights or warnings come on. Aside from lurching a few times whenever I start it up in the morning, it runs fine.