Missing photos from iPhoto

Some of my photos disappeared from iPhoto recently. I did not delete them or format the hard drive. I have been a mac user since 2003 and am fully aware of the mac os and how it stores files. However this issue is new to me I have searched all system folders and packaged contents of iPhotos but the folders are missing? and they are not in the trash can either. Its like there is no record of the photos ever being uploaded except for a blank event in iPhoto events where the photos were originally uploaded and I could view them. Not all photos are missing only the most recent upload. I do not have time machine backups, so can't use this method to recover files, as I have just purchased a new macbook pro and haven't got round to setting up time machine yet (I should have known better). I tried using a 3rd party data scan software package and the software can locate the missing photos! however it will charge me to recover these photos. I don't feel I should pay for a 3rd party solution, because if a 3rd party data recovery package can identify the missing photos, why can't my mac os? has anyone experienced this problem? and are there any data recovery options I have overlooked to restore the photos without using a 3rd party software package?