The only cart around with Real Time Save (the ability to save at any point in the game) as well as a nice GUI and good support is the Cyclo DS. There are two other flashcarts which support the RTS, namely Supercard and EZ Flash V, the Supercard has an extremely bad interface and very hard to manage, especially for beginners. Whilst on the other hand the EZ Flash V tends to be a little slow on updates, also the real time save function is said to not work so well on it.
Although the Cyclo DS would indeed be more expensive than the other 2 options, it would be more suited to your needs.
Although the Cyclo DS would indeed be more expensive than the other 2 options, it would be more suited to your needs.